[gobject-introspection] CI: remove workaround for old meson bug

[Christoph Reiter <creiter src gnome org>]

commit 3b9ae74786c9637c058d771dc9509492c3033503
Author: Christoph Reiter <reiter christoph gmail com>
Date:   Sun Oct 27 10:52:14 2019 +0100

    CI: remove workaround for old meson bug
    
    The different dir separator seems to confuse meson now
    (likely a new change in mingw Python path handling..)

 .gitlab-ci/test-msys2-meson.sh | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)
---
diff --git a/.gitlab-ci/test-msys2-meson.sh b/.gitlab-ci/test-msys2-meson.sh
index 40a3cbce..9c795d33 100644
--- a/.gitlab-ci/test-msys2-meson.sh
+++ b/.gitlab-ci/test-msys2-meson.sh
@@ -34,11 +34,8 @@ export CCACHE_DIR="${CCACHE_BASEDIR}/_ccache"
 pip3 install --upgrade --user meson==0.49.2 flake8
 export PATH="$HOME/.local/bin:$PATH"
 
-# FIXME: https://github.com/Alexpux/MINGW-packages/pull/4064
-# Passing the full interpreter path works around the issue
-PYTHON="$(which python3)"
 export CFLAGS="-Werror"
-meson -Dcairo=enabled -Ddoctool=enabled -Dpython="${PYTHON}" --buildtype debug _build
+meson -Dcairo=enabled -Ddoctool=enabled --buildtype debug _build
 cd _build
 ninja