ci: uninstall php8.1-imagick before build (issue #2009)

When php imagick is installed and when WeeChat is compiled with gcc, there's a
crash when the php plugin is loaded.  Newer versions of gcc should fix the
issue, but as in CI we can't easily use them, uninstalling imagick avoids the
crash.

.github/workflows/ci.yml

@@ -34,6 +34,8 @@ jobs:
       run: |
         sudo apt-get update -qq
         sudo apt-get --yes --no-install-recommends install ${{ env.WEECHAT_DEPENDENCIES }}
+        # uninstall php imagick as is causes a crash when loading php plugin (see #2009)
+        sudo apt-get --yes purge php8.1-imagick
         sudo -H pip3 install --ignore-installed msgcheck
 
     - name: Check gettext files