ci: Fix ci due to aqtinstall action being weird with 6.7

since 6.7 arch changed from gcc_64 to linux_gcc_64 and the action
doesn't automatically handle that. Would have to set an arch per OS.
6.6 is fine for our purposes

.github/workflows/examples.yml

@@ -37,7 +37,7 @@ jobs:
         uses: jurplel/install-qt-action@v4
         if: env.IS_SELFHOSTED != 1
         with:
-          version: 6.7
+          version: 6.6
           cache: true
 
       - name: Make sure MSVC is found when Ninja generator is in use

.github/workflows/flutter-rel.yml

@@ -50,9 +50,14 @@ jobs:
           sudo apt update -qq
           sudo apt install libgtk-3-dev libglib2.0-dev -y
 
-      - name: Install ninja
+      - name: Install ninja (Windows / Linux)
+        if: ${{ runner.os != 'macOS' }}
         uses: turtlesec-no/get-ninja@main
 
+      - name: Install ninja (macOS)
+        if: ${{ runner.os == 'macOS' }}
+        run: brew install ninja
+
       - uses: subosito/flutter-action@v2
         with:
           flutter-version: "3.x"