Bump checkout from v3 to v4

checkout v3 uses node16 which reaches EOL on 15th of Oct 2024
https://github.blog/changelog/2024-09-25-end-of-life-for-actions-node16/

.github/workflows/build.yml

@@ -10,7 +10,7 @@ jobs:
   #   runs-on: macos-12
 
   #   steps:
-  #   - uses: actions/checkout@v3
+  #   - uses: actions/checkout@v4
 
   #   - name: Fetch submodules
   #     run: git submodule init && git submodule update
@@ -130,7 +130,7 @@ jobs:
   #       # Build Artifact of xamarin.android-oss dated 2022-02-16, master branch (= version 12.2.99)
   #       xamarin_url: https://artprodcus3.artifacts.visualstudio.com/Ad0adf05a-e7d7-4b65-96fe-3f3884d42038/6fd3d886-57a5-4e31-8db7-52a1b47c07a8/_apis/artifact/cGlwZWxpbmVhcnRpZmFjdDovL3hhbWFyaW4vcHJvamVjdElkLzZmZDNkODg2LTU3YTUtNGUzMS04ZGI3LTUyYTFiNDdjMDdhOC9idWlsZElkLzU0OTUzL2FydGlmYWN0TmFtZS9pbnN0YWxsZXJzLXVuc2lnbmVkKy0rTGludXg1/content?format=zip
   #   steps:
-  #   - uses: actions/checkout@v3
+  #   - uses: actions/checkout@v4
 
   #   - name: Fetch submodules
   #     run: git submodule init && git submodule update
@@ -254,7 +254,7 @@ jobs:
     runs-on: windows-2022
 
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
 
     - name: Setup Gradle
       uses: gradle/gradle-build-action@v2