JanusGraph-Python 1.1.1 release

[pm-osc]

Notable changes:

• added support for GraphBinary serialization for JanusGraph text predicate and relation identifier
• integration tests are extended with cases for testing relation identifier with string vertex ID

[porunov]

LGTM. Thank you @pm-osc !
@FlorianHockmann should we manually create a 1.1.1 release afterwards to trigger the release workflow?

[FlorianHockmann]

should we manually create a 1.1.1 release afterwards to trigger the release workflow?

Yes, I can do that directly after merging this.

edit: I omitted the second point from the notable changes as I consider tests to be something only relevant for us internally during development.