Pin swift version (#671)

Author: fabianbs96

.github/workflows/ci.yml

@@ -55,6 +55,8 @@ jobs:
               libclang-rt-14-dev
 
       - uses: swift-actions/setup-swift@v1
+        with:
+          swift-version: "5.8.1"
       - name: Building Phasar in ${{ matrix.build }} with ${{ matrix.compiler[0] }}
         env:
           BUILD_TYPE: ${{ matrix.build }}