.github: prevent both jobs from using caching

A recent change upgraded us to setup-go@v4,
but failed to keep the "test" job without the use of any caching.
Rename it to keep that clear.

Author: mvdan

.github/workflows/test.yml

@@ -1,7 +1,7 @@
 on: [push, pull_request]
 name: Test
 jobs:
-  test:
+  test-nocache:
     strategy:
       matrix:
         go-version: [1.20.x, 1.21.x]
@@ -12,6 +12,7 @@ jobs:
     - uses: actions/setup-go@v4
       with:
         go-version: ${{ matrix.go-version }}
+        cache: false
     - run: go test ./...
 
   test-cache: