Update Swift version matrix in Ubuntu build workflow

Author: makoni

.github/workflows/build-ubuntu.yml

@@ -11,7 +11,7 @@ jobs:
     name: Build on Ubuntu with Swift ${{ matrix.swift }}
     strategy:
       matrix:
-        swift: ["6.0", "6.1"]
+        swift: ["6.1", "6.2"]
     runs-on: ubuntu-latest
     container: 
       image: swift:${{ matrix.swift }}