Use v3 of checkout action in GitHub CI builds

The previously used v2 uses node12 which is being deprecated by GitHub
and won't be any longer available soon, so switch to the currently
supported version.

.github/workflows/ci.yml

@@ -164,7 +164,7 @@ jobs:
           esac
 
       - name: Checkout
-        uses: actions/checkout@v2
+        uses: actions/checkout@v3
         with:
           submodules: 'recursive'
 

.github/workflows/ci_cmake.yml

@@ -87,7 +87,7 @@ jobs:
 
     steps:
       - name: Checkout
-        uses: actions/checkout@v2
+        uses: actions/checkout@v3
         with:
           submodules: 'recursive'
 

.github/workflows/ci_mac.yml

@@ -114,7 +114,7 @@ jobs:
 
     steps:
     - name: Checkout
-      uses: actions/checkout@v2
+      uses: actions/checkout@v3
       with:
         submodules: recursive
 

.github/workflows/ci_mac_xcode.yml

@@ -108,7 +108,7 @@ jobs:
 
     steps:
     - name: Checkout
-      uses: actions/checkout@v2
+      uses: actions/checkout@v3
       with:
         submodules: recursive
 

.github/workflows/ci_msw.yml

@@ -69,7 +69,7 @@ jobs:
 
     steps:
       - name: Checkout
-        uses: actions/checkout@v2
+        uses: actions/checkout@v3
         with:
           submodules: 'recursive'
 

.github/workflows/ci_msw_cross.yml

@@ -129,7 +129,7 @@ jobs:
           echo "wxTEST_RUNNER=${winerun}" >> $GITHUB_ENV
 
       - name: Checkout
-        uses: actions/checkout@v2
+        uses: actions/checkout@v3
         with:
           submodules: 'recursive'
 

.github/workflows/code_checks.yml

@@ -19,7 +19,7 @@ jobs:
 
     steps:
       - name: Checkout
-        uses: actions/checkout@v2
+        uses: actions/checkout@v3
 
       - name: Install codespell
         run: |
@@ -36,7 +36,7 @@ jobs:
 
     steps:
       - name: Checkout
-        uses: actions/checkout@v2
+        uses: actions/checkout@v3
 
       - name: Check for trailing whitespace and TABs
         run: |
@@ -65,7 +65,7 @@ jobs:
 
     steps:
       - name: Checkout
-        uses: actions/checkout@v2
+        uses: actions/checkout@v3
 
       - name: Install dos2unix
         run: |

.github/workflows/docs_update.yml

@@ -28,7 +28,7 @@ jobs:
 
     steps:
       - name: Checkout
-        uses: actions/checkout@v2
+        uses: actions/checkout@v3
 
       - name: Install doxygen
         run: |

.github/workflows/make_release.yml

@@ -18,7 +18,7 @@ jobs:
 
     steps:
       - name: Checkout
-        uses: actions/checkout@v2
+        uses: actions/checkout@v3
         with:
           submodules: 'recursive'
 
@@ -75,7 +75,7 @@ jobs:
 
     steps:
       - name: Checkout
-        uses: actions/checkout@v2
+        uses: actions/checkout@v3
 
       - name: Download Release Archive
         uses: actions/download-artifact@v3