decouple py and c# versions in update script (#3790)

utils/validate_versions.py

     return True
 
 
-def set_version(new_version: str) -> None:
-    new_contents = f'{VERSION_LINE_START}"{new_version}"\n'
+def set_version(python_version: str, csharp_version: str) -> None:
+    new_contents = f'{VERSION_LINE_START}"{python_version}"\n'
-        print(f"Setting {path} to version {new_version}")
+        print(f"Setting {path} to version {python_version}")
-    # Package version is a bit stricter - only set it if we're not a "dev" version.
-    if "dev" not in new_version:
-        package_version = new_version + "-preview"
+
+    if csharp_version is not None:
+        package_version = csharp_version + "-preview"
         print(
             f"Setting package version to {package_version} in {UNITY_PACKAGE_JSON_PATH}"
         )
 
 if __name__ == "__main__":
     parser = argparse.ArgumentParser()
-    parser.add_argument("--new-version", default=None)
+    parser.add_argument("--python-version", default=None)
+    parser.add_argument("--csharp-version", default=None)
-    if args.new_version:
-        print(f"Updating to verison {args.new_version}")
-        set_version(args.new_version)
+
+    if args.python_version:
+        print(f"Updating python library to version {args.python_version}")
+        if args.csharp_version:
+            print(f"Updating C# package to version {args.csharp_version}")
+        set_version(args.python_version, args.csharp_version)
     else:
         ok = check_versions()
         return_code = 0 if ok else 1