chore(ci): set golang version explicitly to 1.18 (#1952)

We were unintentionally doing that because ^1.17 was pulling 1.18.x

.github/workflows/code-coverage.yml

@@ -14,7 +14,7 @@ jobs:
     - name: Set up Go.
       uses: actions/setup-go@v3
       with:
-        go-version: ^1.17
+        go-version: '1.18'
       id: go
     - name: Check out code into the Go module directory
       uses: actions/checkout@v3