Use jdpurcell's patch on linux-arm runners for now

At least until jurplel/install-qt-action#248
is resolved.

.github/workflows/build.yaml

@@ -74,7 +74,12 @@ jobs:
           sudo apt install qt6-{base-{dev{,-tools},doc-dev},connectivity-{dev,doc-html},l10n-tools,tools-dev{,-tools}}
       - name: Install online Qt version
         if: contains(matrix.qt, '.') # ie if not using Ubuntu's Qt5/Qt6.
-        uses: jurplel/install-qt-action@v4
+        # \todo Revert to only using jurplel's action when issue #248 is resolved.
+        #       Note, can probably remove the host property below at the same time.
+        # \todo See https://github.com/jurplel/install-qt-action/issues/248
+        uses: >-
+          ${{ matrix.arch == 'arm64' && 'jdpurcell/install-qt-action@b45c67aaa9e0ea77e59a7031ec14a12d5ddf4b35'
+                                     || 'jurplel/install-qt-action@v4' }}
         with:
           version: ${{ matrix.qt }}
           host: linux${{ matrix.arch == 'arm64' && '_arm64' || '' }}