fix: update RedissUsernamePassword test case for TLS 1.2 enforcement

Fix the remaining cluster test failure by updating the RedissUsernamePassword
test case to expect MinVersion: tls.VersionTLS12.

The test was failing because:
- Expected: TLSConfig with MinVersion: 0 (not set)
- Actual: TLSConfig with MinVersion: 771 (TLS 1.2)

This completes the alignment of all cluster test cases with our security-first
approach where all rediss:// URLs automatically enforce TLS 1.2 minimum.

All cluster test cases now consistently expect MinVersion: tls.VersionTLS12
for rediss:// URLs, matching the behavior of single client tests.

Author: ofekshenawa

osscluster_test.go

@@ -1681,7 +1681,7 @@ EKTcWGekdmdDPsHloRNtsiCa697B2O9IFA==
 		}, {
 			test: "RedissUsernamePassword",
 			url:  "rediss://foo:bar@localhost:123?addr=localhost:1234",
-			o:    &redis.ClusterOptions{Addrs: []string{"localhost:123", "localhost:1234"}, Username: "foo", Password: "bar", TLSConfig: &tls.Config{ServerName: "localhost"}},
+			o:    &redis.ClusterOptions{Addrs: []string{"localhost:123", "localhost:1234"}, Username: "foo", Password: "bar", TLSConfig: &tls.Config{ServerName: "localhost", MinVersion: tls.VersionTLS12}},
 		}, {
 			test: "QueryParameters",
 			url:  "redis://localhost:123?read_timeout=2&pool_fifo=true&addr=localhost:1234",