Update GitHub actions to avoid deprecated Node version

Following Node12's deprecation by GitHub, we started getting the
following message:
```
create_new_rule
The following actions uses node12 which is deprecated and will be forced to run on node16: actions/checkout@v2, actions/setup-python@v2. For more info: https://github.blog/changelog/2023-06-13-github-actions-all-actions-will-run-on-node16-instead-of-node12-by-default/
```

From the doc of these actions, it looks like just upgrading the versions
should work transparently.

.github/workflows/add_language.yml

@@ -19,13 +19,13 @@ jobs:
       GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
 
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v4
       with:
         persist-credentials: true
         ref: master
         path: 'rspec'
 
-    - uses: actions/setup-python@v2
+    - uses: actions/setup-python@v4
       with:
         python-version: '3.9'
 

.github/workflows/create_new_rspec.yml

@@ -16,13 +16,13 @@ jobs:
       GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
 
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v4
       with:
         persist-credentials: true
         ref: master
         path: 'rspec'
 
-    - uses: actions/setup-python@v2
+    - uses: actions/setup-python@v4
       with:
         python-version: '3.9'
 

.github/workflows/main.yml

@@ -13,7 +13,7 @@ jobs:
       contents: write # Get the contents of open new-rule PRs, the 'master'; write to 'gh-pages' branch
     steps:
       - name: Checkout 🛎️
-        uses: actions/checkout@v2 # If you're using actions/checkout@v2 you must set persist-credentials to false in most cases for the deployment to work correctly.
+        uses: actions/checkout@v4 # If you're using actions/checkout you must set persist-credentials to false in most cases for the deployment to work correctly.
         with:
           persist-credentials: false
           ref: 'master'

.github/workflows/update_coverage.yml

@@ -10,14 +10,14 @@ jobs:
       TMP_BRANCH: temporary/coverage_update
 
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v4
       with:
         persist-credentials: true
         ref: master
         path: 'rspec'
         token: ${{ secrets.COVERAGE_GITHUB_TOKEN }}
 
-    - uses: actions/setup-python@v2
+    - uses: actions/setup-python@v4
       with:
         python-version: '3.9'