Remove Flatpak version requirement notice from README

Add check build using minimum required QT version

.github/workflows/build.yml

@@ -71,6 +71,13 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
+        qt:
+          - version: 5.15.2
+            check_only: false
+
+          - version: 5.12.0
+            check_only: true
+
         env:
           - name: linux
             os: ubuntu-latest
@@ -92,6 +99,7 @@ jobs:
             ninja_platform: win
             qt_platform: windows
             qt_arch: win64_msvc2019_64
+            qt_arch_check_only: win64_msvc2017_64
             openssl_arch: VC-WIN64A
             msvc_arch: x64
             cmake_env:
@@ -104,6 +112,7 @@ jobs:
             ninja_platform: win
             qt_platform: windows
             qt_arch: win32_msvc2019
+            qt_arch_check_only: win32_msvc2017
             openssl_arch: VC-WIN32
             msvc_arch: x86
             cmake_env:
@@ -133,14 +142,27 @@ jobs:
       - name: Install Qt
         uses: jurplel/install-qt-action@v2.13.0
         timeout-minutes: 10
+        if: "!matrix.qt.check_only"
         with:
-          version: 5.15.2
+          version: ${{ matrix.qt.version }}
           target: desktop
           host: ${{ matrix.env.qt_platform }}
           arch: ${{ matrix.env.qt_arch }}
           install-deps: true
           modules: qtwebengine
 
+      - name: Install Qt
+        uses: jurplel/install-qt-action@v2.13.0
+        timeout-minutes: 10
+        if: matrix.qt.check_only
+        with:
+          version: ${{ matrix.qt.version }}
+          target: desktop
+          host: ${{ matrix.env.qt_platform }}
+          arch: ${{ matrix.env.qt_arch_check_only }}
+          install-deps: true
+          modules: qtwebengine
+
       - name: Install Ninja
         uses: seanmiddleditch/gha-setup-ninja@v3
         with:
@@ -199,7 +221,7 @@ jobs:
           ninja package
 
       - name: Publish build artifacts
-        if: matrix.env.pack
+        if: matrix.env.pack && !matrix.qt.check_only
         uses: actions/upload-artifact@v2
         with:
           path: build/release/pack/Gittyup-*

README.md

@@ -45,7 +45,7 @@ submodules are optional or may also be satisfied by system libraries.
 
 **External Dependencies**
 
-* Qt (required >= 5.12; for Flatpak >= 5.15)
+* Qt (required >= 5.12)
 
 **Included Dependencies**