chore: bump action versions

I think this should fix the unicode import error in https://github.com/google/addlicense/actions/runs/2198105433

.github/workflows/tests.yaml

@@ -24,13 +24,13 @@ jobs:
       with:
         access_token: ${{ github.token }}
 
-    - uses: actions/setup-go@v2
+    - uses: actions/setup-go@v3
       with:
         go-version: ${{ matrix.go-version }}
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v3
 
     - name: Cache go modules
-      uses: actions/cache@v2
+      uses: actions/cache@v3
       with:
         path: |
           ~/.cache/go-build
@@ -43,4 +43,4 @@ jobs:
 
     - name: Upload coverage to Codecov
       if: ${{ matrix.update-coverage }}
-      uses: codecov/codecov-action@v2
+      uses: codecov/codecov-action@v3