GHA: update checkout and cache actions to v3

Avoids warnings because of deprecated Node.js version.

Signed-off-by: Frank Lichtenheld <frank@lichtenheld.com>

.github/workflows/msbuild.yml

@@ -22,7 +22,7 @@ jobs:
     name: 'msvc - ${{matrix.arch}} ${{ matrix.ovpn3.name }}'
     runs-on: windows-latest
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v3
     - uses: lukka/get-cmake@latest
 
     - name: Restore artifacts, or setup vcpkg (do not install any package)
@@ -65,7 +65,7 @@ jobs:
       - name: Install dependencies
         run: sudo apt update && sudo apt install -y mingw-w64 libtool automake autoconf
       - name: Checkout
-        uses: actions/checkout@v2
+        uses: actions/checkout@v3
         with:
           path: openvpn-gui
 
@@ -75,7 +75,7 @@ jobs:
 
       - name: Cache dependencies
         id: cache
-        uses: actions/cache@v2
+        uses: actions/cache@v3
         with:
           path: '~/mingw/'
           key: mingw-${{ matrix.target }}