Update atproto.py

[MarkWieczorek]

There is an extra space in the bridged profile text on bluesky that looks like this:

[bridged from solarsystem.social/@mrak on the fediverse by fed.brid.gy ]

I think that this PR fixes this minor annoyance.

[snarfed]

Thank you for the contribution! Sadly this space is necessary; without it, Bluesky's auto-linker includes the closing brace in the URL it links to. I'll add a comment saying that.

[MarkWieczorek]

Ok. Then here are some alternatives:

1. No brackets at all: Bridged from solarsystem.social/@mrak on the fediverse by fed.brid.gy
2. Reworded: Bridged by fed.brid.gy from solarsystem.social/@mrak on the fediverse.
3. Reworded: This account is bridged from solarsystem.social/@mrak on the fediverse by fed.brid.gy