Drop the set-output command which will be disabled

.github/update.py

@@ -38,7 +38,7 @@ def fetch_latest_release():
 def main():
     version, sha256 = fetch_latest_release()
     if os.getenv("GITHUB_ACTIONS"):
-        print(f"::set-output name=NETBIRD_VERSION::{version}")
+        print(f"NETBIRD_VERSION={version}", file=open(os.environ["GITHUB_OUTPUT"], "a"))
 
     with open("netbird/Makefile") as f:
         makefile = f.read()