minor #17859 Use actions/checkout@v3 (OskarStark)

This PR was merged into the 5.4 branch.

Discussion
----------

Use `actions/checkout@v3`

Commits
-------

af85ac6 Use `actions/checkout@v3`

Author: OskarStark

.github/workflows/ci.yaml

@@ -21,7 +21,7 @@ jobs:
 
         steps:
             -   name: "Checkout"
-                uses: actions/checkout@v2
+                uses: actions/checkout@v3
 
             -   name: "Set-up PHP"
                 uses: shivammathur/setup-php@v2
@@ -57,7 +57,7 @@ jobs:
 
         steps:
             -   name: "Checkout"
-                uses: actions/checkout@v2
+                uses: actions/checkout@v3
 
             -   name: "Create cache dir"
                 run: mkdir .cache
@@ -83,7 +83,7 @@ jobs:
         continue-on-error: true
         steps:
           - name: Checkout code
-            uses: actions/checkout@v2
+            uses: actions/checkout@v3
             with:
                 path: 'docs'