Bump versions of github actions.

This updates actions/checkout, actions/setup-python, actions/setup-node,
and actions/cache to their most recent releases.

.github/workflows/test.yml

@@ -30,15 +30,15 @@ jobs:
             django-version: '3.1'
 
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v3
 
     - name: Set up Python ${{ matrix.python-version }}
-      uses: actions/setup-python@v2
+      uses: actions/setup-python@v3
       with:
         python-version: ${{ matrix.python-version }}
 
     - name: Set up Node
-      uses: actions/setup-node@v1
+      uses: actions/setup-node@v3
       with:
         node-version: '16'
 
@@ -51,7 +51,7 @@ jobs:
         echo "::set-output name=dir::$(pip cache dir)"
 
     - name: Cache
-      uses: actions/cache@v2
+      uses: actions/cache@v3
       with:
         path: ${{ steps.pip-cache.outputs.dir }}
         key: