[pygobject] Drop support for Python 3.6

[Christoph Reiter <creiter src gnome org>]

commit f9425cfc040f720acd2c78b200d2b7c868f44d4e
Author: Christoph Reiter <reiter christoph gmail com>
Date:   Sun Sep 19 15:00:02 2021 +0200

    Drop support for Python 3.6
    
    It will be EOL before the next release.
    This means Ubuntu 18.04 (without backports) is no longer supported,
    we will move to Debian Buster as the new oldest tested target.

 .gitlab-ci.yml               | 9 ++-------
 .gitlab-ci/Dockerfile        | 1 -
 .gitlab-ci/Dockerfile.old    | 2 +-
 .gitlab-ci/run-docker-old.sh | 2 +-
 .gitlab-ci/run-docker.sh     | 2 +-
 PKG-INFO.in                  | 2 +-
 README.rst                   | 2 +-
 meson.build                  | 4 ++--
 pyproject.toml               | 2 +-
 9 files changed, 10 insertions(+), 16 deletions(-)
---
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 81864207..97a3cae0 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -1,4 +1,4 @@
-image: registry.gitlab.gnome.org/gnome/pygobject/main:v16
+image: registry.gitlab.gnome.org/gnome/pygobject/main:v17
 
 stages:
   - build_and_test
@@ -62,11 +62,6 @@ mingw64:
     MSYSTEM: "MINGW64"
   <<: *mingw-defaults
 
-python3.6:
-  variables:
-    PYENV_VERSION: "3.6.14"
-  <<: *defaults
-
 python3.7:
   variables:
     PYENV_VERSION: "3.7.11-debug"
@@ -95,7 +90,7 @@ pypy3.7:
 
 old-i386-py3:
   stage: build_and_test
-  image: registry.gitlab.gnome.org/gnome/pygobject/old:v4
+  image: registry.gitlab.gnome.org/gnome/pygobject/old:v5
   artifacts:
     paths:
       - coverage/
diff --git a/.gitlab-ci/Dockerfile b/.gitlab-ci/Dockerfile
index e10aaa97..5a4e0e72 100644
--- a/.gitlab-ci/Dockerfile
+++ b/.gitlab-ci/Dockerfile
@@ -42,7 +42,6 @@ ENV PYTHON_CONFIGURE_OPTS="--enable-shared"
 RUN curl -L https://raw.githubusercontent.com/pyenv/pyenv-installer/master/bin/pyenv-installer | bash
 
 RUN pyenv install pypy3.7-7.3.5
-RUN pyenv install 3.6.14
 RUN pyenv install --debug 3.7.11
 RUN pyenv install --debug 3.8.12
 RUN pyenv install --debug 3.9.7
diff --git a/.gitlab-ci/Dockerfile.old b/.gitlab-ci/Dockerfile.old
index beffb9be..3e7b8f82 100644
--- a/.gitlab-ci/Dockerfile.old
+++ b/.gitlab-ci/Dockerfile.old
@@ -1,4 +1,4 @@
-FROM i386/ubuntu:bionic
+FROM i386/debian:buster
 
 ENV DEBIAN_FRONTEND=noninteractive
 
diff --git a/.gitlab-ci/run-docker-old.sh b/.gitlab-ci/run-docker-old.sh
index bd11cbff..32b37156 100755
--- a/.gitlab-ci/run-docker-old.sh
+++ b/.gitlab-ci/run-docker-old.sh
@@ -2,7 +2,7 @@
 
 set -e
 
-TAG="registry.gitlab.gnome.org/gnome/pygobject/old:v4"
+TAG="registry.gitlab.gnome.org/gnome/pygobject/old:v5"
 
 sudo docker build --build-arg HOST_USER_ID="$UID" --tag "${TAG}" \
     --file "Dockerfile.old" .
diff --git a/.gitlab-ci/run-docker.sh b/.gitlab-ci/run-docker.sh
index 48c3036f..e6aaaa0b 100755
--- a/.gitlab-ci/run-docker.sh
+++ b/.gitlab-ci/run-docker.sh
@@ -2,7 +2,7 @@
 
 set -e
 
-TAG="registry.gitlab.gnome.org/gnome/pygobject/main:v16"
+TAG="registry.gitlab.gnome.org/gnome/pygobject/main:v17"
 
 sudo docker build --build-arg HOST_USER_ID="$UID" --tag "${TAG}" \
     --file "Dockerfile" .
diff --git a/PKG-INFO.in b/PKG-INFO.in
index fd6096ad..9bbfb092 100644
--- a/PKG-INFO.in
+++ b/PKG-INFO.in
@@ -18,4 +18,4 @@ Classifier: Operating System :: Microsoft :: Windows
 Classifier: Programming Language :: C
 Classifier: Programming Language :: Python
 Classifier: Topic :: Software Development :: Libraries :: Python Modules
-Requires-Python: >=3.6, <4
+Requires-Python: >=3.7, <4
diff --git a/README.rst b/README.rst
index 9158a78c..f8fe26b7 100644
--- a/README.rst
+++ b/README.rst
@@ -12,7 +12,7 @@
 <https://developer.gnome.org/glib/stable/>`__, `GIO
 <https://developer.gnome.org/gio/stable/>`__ and many more.
 
-It supports Linux, Windows and macOS and works with **Python 3.6+** and
+It supports Linux, Windows and macOS and works with **Python 3.7+** and
 **PyPy3**. PyGObject, including this documentation, is licensed under the
 **LGPLv2.1+**.
 
diff --git a/meson.build b/meson.build
index e1e3cf9d..fd8473a9 100644
--- a/meson.build
+++ b/meson.build
@@ -15,8 +15,8 @@ platform_version = '@0@.0'.format(pygobject_version_major)
 pymod = import('python')
 python = pymod.find_installation(get_option('python'))
 
-if python.language_version().version_compare('< 3.6')
-  error('Requires Python >= 3.6')
+if python.language_version().version_compare('< 3.7')
+  error('Requires Python >= 3.7')
 endif
 
 python_dep = python.dependency()
diff --git a/pyproject.toml b/pyproject.toml
index f5eec800..a6bf6918 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -5,7 +5,7 @@ description = "Python bindings for GObject Introspection"
 authors = ["Christoph Reiter"]
 
 [tool.poetry.dependencies]
-python = "^3.6"
+python = "^3.7"
 pycairo = "^1.16"
 
 [tool.poetry.dev-dependencies]