fix: adapt mysql and ruby test assertions

MySQL CONCAT with binary params returns VARBINARY, causing base64
encoding. Use CAST(... AS CHAR) to force character type output.
Ruby executor doesn't support keyword parameters (name:), use
positional parameters instead.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

backend/tests/worker.rs

@@ -1346,7 +1346,7 @@ async fn test_mysql_job(db: Pool<Postgres>) -> anyhow::Result<()> {
 
     let content = r#"
 -- ? name (varchar)
-SELECT CONCAT('hello ', ?) AS result;
+SELECT CAST(CONCAT('hello ', ?) AS CHAR) AS result;
 "#
     .to_owned();
 
@@ -1492,7 +1492,7 @@ async fn test_ruby_job(db: Pool<Postgres>) -> anyhow::Result<()> {
     let port = server.addr.port();
 
     let content = r#"
-def main(name:)
+def main(name)
   "hello #{name}"
 end
 "#
@@ -3346,7 +3346,9 @@ async fn test_duckdb_ffi(db: Pool<Postgres>) -> anyhow::Result<()> {
 #[cfg(feature = "deno_core")]
 #[sqlx::test(fixtures("base"))]
 async fn test_flow_substep_tag_availability_check(db: Pool<Postgres>) -> anyhow::Result<()> {
-    use windmill_common::worker::{CustomTags, SpecificTagData, SpecificTagType, CUSTOM_TAGS_PER_WORKSPACE};
+    use windmill_common::worker::{
+        CustomTags, SpecificTagData, SpecificTagType, CUSTOM_TAGS_PER_WORKSPACE,
+    };
 
     initialize_tracing().await;
 
@@ -3387,15 +3389,16 @@ async fn test_flow_substep_tag_availability_check(db: Pool<Postgres>) -> anyhow:
             .await;
 
     // The flow should fail because the tag is not available for test-workspace
-    assert!(!result.success, "Flow should have failed due to unavailable tag");
+    assert!(
+        !result.success,
+        "Flow should have failed due to unavailable tag"
+    );
 
     let result_json = result.json_result();
     assert!(result_json.is_some(), "Result should have error details");
 
     let error_result = result_json.unwrap();
-    let error_message = error_result["error"]["message"]
-        .as_str()
-        .unwrap_or("");
+    let error_message = error_result["error"]["message"].as_str().unwrap_or("");
 
     // Verify the error is about tag availability
     assert!(