[gnome-runtime-images] Add GNOME 3.30 runtime image

[Jordan Petridis <jpetridis src gnome org>]

commit 537f693720b1ff04782e6097f393acb36976a8d5
Author: Jordan Petridis <jpetridis gnome org>
Date:   Mon Oct 1 23:36:01 2018 +0300

    Add GNOME 3.30 runtime image

 .gitlab-ci.yml        | 9 +++++++++
 gnome-3-30/Dockerfile | 3 +++
 2 files changed, 12 insertions(+)
---
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index e9cff17..d7004d9 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -65,6 +65,15 @@ gnome:3.28:
         - export OCI_YML=gnome-3-28/Dockerfile
     <<: *build
 
+gnome:3.30:
+    stage: runtimes
+    before_script:
+        # https://stackoverflow.com/questions/2264428/converting-string-to-lower-case-in-bash#2264537
+        - export NAMESPACE="$(echo "${CI_PROJECT_NAMESPACE}" | tr A-Z a-z)"
+        - export IMAGE="${CI_REGISTRY}/${NAMESPACE}/${CI_PROJECT_NAME}/gnome:3.30"
+        - export OCI_YML=gnome-3-30/Dockerfile
+    <<: *build
+
 rust master:
     stage: rust_bundle
     before_script:
diff --git a/gnome-3-30/Dockerfile b/gnome-3-30/Dockerfile
new file mode 100644
index 0000000..aed8122
--- /dev/null
+++ b/gnome-3-30/Dockerfile
@@ -0,0 +1,3 @@
+FROM registry.gitlab.gnome.org/gnome/gnome-runtime-images/base
+
+RUN flatpak install -y flathub org.gnome.Sdk//3.30 org.gnome.Sdk.Debug//3.30  org.gnome.Platform//3.30