Set Bytes Json Schema to base64

[HonakerM]

What this PR does / why we need it:
This PR sets the pydantic bytes json schema to base64. This updates the auto-generated openapi docs to correctly list bytes fields as base64 formatted strings instead of raw binary strings.

Special notes for your reviewer:
I discovered this config while exploring the pydantic repo. The PR that created the config was only merged last week so it hasn't been released. I tested my changes with a local clone of pydantic and ConfigDict is backwards compatible so this should be safe to merge but for abundance of caution this PR can wait until an official version is released.

If applicable:

• this PR contains documentation
• this PR contains unit tests
• this PR has been tested for backwards compatibility

[prashantgupta24]

This is awesome, thanks @HonakerM ! Yeah we can wait for the official release!

[gabe-l-hart]

@HonakerM I tried to resolve the conflicts, but apparently my mental black execution failed. Can you run fmt.sh on the latest tip of this branch since it's in your fork?

[gabe-l-hart]

@HonakerM It looks like the test failures are legitimate (I was distracted by the warning about the invalid escape sequence). If this is still important, can you look into getting those fixed?

[HonakerM]

@gabe-l-hart Okay I'll take a look! This change isn't the most pressing so I'm not sure when I'll get to it but it'd probably be nice to have.

[gabe-l-hart]

@HonakerM Do you still need this one? It looks like it could use a rebase and some test fixes if so

[HonakerM]

@gabe-l-hart it's not required but would be nice. I just rebased/updated version, I'll keep an eye out for test failures

[gabe-l-hart]

Closing as stale. @HonakerM we can revisit later if this becomes urgent