fix(cicd): use latest meson

The GitHub action BSFishy/meson-build doesn't seem maintained anymore,
so I installed the package myself and followed the instructions in our
own README.md.

.github/workflows/ci.yml

@@ -43,21 +43,11 @@ jobs:
     - uses: actions/setup-python@v4
       with:
           python-version: '3.8'
-
-    - name: Install dependencies
-      run: |
-        sudo apt-get -y install appstream appstream-util desktop-file-utils gettext
-
-    - name: Meson build
-      uses: BSFishy/meson-build@v1.0.3
-      with:
-        action: build
-        setup-options: --prefix=/tmp/diffuse
-
-    - name: Meson test
-      uses: BSFishy/meson-build@v1.0.3
-      with:
-        action: test
+    - run: sudo apt-get -y install meson appstream appstream-util desktop-file-utils gettext
+    - run: pip install meson ninja
+    - run: meson setup build
+    - run: meson compile -C build
+    - run: meson test -C build
 
   flatpak-build-test:
     runs-on: ubuntu-latest

meson.build

@@ -1,6 +1,6 @@
 project('diffuse',
     version: '0.7.7',
-    meson_version: '>= 0.50',
+    meson_version: '>= 0.55',
     license: 'GPL-2.0-or-later',
     default_options: [ 'warning_level=2' ])