Fix syntax

Author: krassowski

about.html

@@ -441,7 +441,7 @@
     affiliation: Quansight
     photo: Michal_Krassowski.jpg
     mastodon: https://fosstodon.org/@krassowski
-    bluesky_handle: @krassowski.bsky.social
+    bluesky_handle: krassowski.bsky.social
     gh_handle: krassowski
     linkedin: https://www.linkedin.com/in/michal-krassowski/
     subproject: Jupyter Frontends