Fix CI Go tool installs

.github/workflows/tests.yml

@@ -50,10 +50,10 @@ jobs:
       - name: Install coverage tools
         if: ${{ matrix.test-type == 'coverage' }}
         run: |
-          go get github.com/axw/gocov/gocov
-          go get github.com/modocache/gover
-          go get github.com/mattn/goveralls
-          go get golang.org/x/tools/cmd/cover
+          go install github.com/axw/gocov/gocov@latest
+          go install github.com/modocache/gover@latest
+          go install github.com/mattn/goveralls@latest
+          go install golang.org/x/tools/cmd/cover@latest
 
       - name: Check environment
         run: |