Align release builds with CI workflow

Previously, the release builds were based on the local development
workflow. However, it is more appropriate to build them the same way
they are tested by the CI workflow.

.github/workflows/robotmk.yaml

@@ -11,7 +11,7 @@ on:
 
 jobs:
   build_robotmk_from_source:
-    runs-on: ubuntu-latest
+    runs-on: windows-latest
 
     steps:
       - name: "Checkout repository"
@@ -22,9 +22,6 @@ jobs:
         with:
           target: x86_64-pc-windows-gnu
 
-      - name: "Install MinGW-w64"
-        run: sudo apt-get install -y mingw-w64
-
       - name: "Build Robotmk Windows"
         working-directory: ${{ github.workspace }}/v2/robotmk/
         run: cargo build --target=x86_64-pc-windows-gnu --release