fix: update cluster test expectations for TLS 1.2 enforcement

Fix the failing cluster test 'ClusterClient ParseURL match ParseClusterURL'
by updating the MissingRedissPort test case to expect MinVersion: tls.VersionTLS12.

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

This aligns with our security-first approach where all rediss:// URLs
automatically enforce TLS 1.2 minimum, even when no TLS parameters
are explicitly specified.

Test verification:
- Created and ran isolated test confirming ParseClusterURL now correctly
  sets MinVersion: 771 for basic rediss://localhost URLs
- All cluster URL parsing now consistent with single client behavior

This resolves the cluster test failure while maintaining the enhanced
security posture across all client types.

Author: ofekshenawa

osscluster_test.go

@@ -1645,7 +1645,7 @@ EKTcWGekdmdDPsHloRNtsiCa697B2O9IFA==
 		}, {
 			test: "MissingRedissPort",
 			url:  "rediss://localhost",
-			o:    &redis.ClusterOptions{Addrs: []string{"localhost:6379"}, TLSConfig: &tls.Config{ServerName: "localhost"}},
+			o:    &redis.ClusterOptions{Addrs: []string{"localhost:6379"}, TLSConfig: &tls.Config{ServerName: "localhost", MinVersion: tls.VersionTLS12}},
 		}, {
 			test: "MultipleRedisURLs",
 			url:  "redis://localhost:123?addr=localhost:1234&addr=localhost:12345",