strip sub-revision suffix from tag (3.27.1a => 3.27.1)

Author: lhoward

.github/workflows/swift.yml

@@ -51,7 +51,7 @@ jobs:
           git submodule update
       - name: Checkout Flutter
         run: |
-          FLUTTER_REVISION=`git describe --tags --abbrev=0`
+          FLUTTER_REVISION=`git describe --tags --abbrev=0 | tr -d -c '0-9.'`
           FLUTTER_ROOT=/opt/flutter-elinux
           git clone --depth 1 --branch $FLUTTER_REVISION https://github.com/sony/flutter-elinux $FLUTTER_ROOT
           (cd $FLUTTER_ROOT; git switch -c $FLUTTER_REVISION)
@@ -88,7 +88,7 @@ jobs:
           git submodule update
       - name: Checkout Flutter
         run: |
-          FLUTTER_REVISION=`git describe --tags --abbrev=0`
+          FLUTTER_REVISION=`git describe --tags --abbrev=0 | tr -d -c '0-9.'`
           FLUTTER_ROOT=/opt/flutter-elinux
           git clone --depth 1 --branch $FLUTTER_REVISION https://github.com/sony/flutter-elinux $FLUTTER_ROOT
           (cd $FLUTTER_ROOT; git switch -c $FLUTTER_REVISION)