gopls/internal/regtest: TestRenamePackage passes with go 1.16

Instead of skipping the test, insist on 1.16 or later.

See golang/go#41061

Change-Id: Ie13f114039693993d65333ab9194629187a9b6b1
Reviewed-on: https://go-review.googlesource.com/c/tools/+/274533
Run-TryBot: Peter Weinberger <pjw@google.com>
gopls-CI: kokoro <noreply+kokoro@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Trust: Peter Weinberger <pjw@google.com>
Reviewed-by: Rebecca Stambler <rstambler@golang.org>

gopls/internal/regtest/diagnostics_test.go

@@ -1434,7 +1434,7 @@ func main() {
 // have no more complaints about it.
 // https://github.com/golang/go/issues/41061
 func TestRenamePackage(t *testing.T) {
-	t.Skip("Waiting for the fix that makes this pass: https://github.com/golang/go/issues/41061")
+	testenv.NeedsGo1Point(t, 16)
 
 	const contents = `
 -- go.mod --