build: downgrade actions/checkout version for improved compatibility

Author: roboticswithjulia

.github/workflows/rust-minimal.yml

@@ -35,7 +35,7 @@ jobs:
     container:
       image: ${{ matrix.docker_image }}
     steps:
-    - uses: actions/checkout@v4
+    - uses: actions/checkout@v2
       with:
         persist-credentials: false # otherwise, the token used is the GITHUB_TOKEN, instead of your personal token
         fetch-depth: 0 # otherwise, you will failed to push refs to dest repo

.github/workflows/rust-stable.yml

@@ -35,7 +35,7 @@ jobs:
     container:
       image: ${{ matrix.docker_image }}
     steps:
-    - uses: actions/checkout@v4
+    - uses: actions/checkout@v2
       with:
         persist-credentials: false # otherwise, the token used is the GITHUB_TOKEN, instead of your personal token
         fetch-depth: 0 # otherwise, you will failed to push refs to dest repo