adds release workflows

[andkononykhin]

Implements logic of release flows as follows:

• PR to stable:
  • job: fail the pipeline unless the current version is different than the latest tag
    • follow-up: current version should be higher
• push to stable / manual re-run:
  • job: idempotence checks
    • GitHub latest release check: whether it is the same as the current version
    • whether PyPI release includes the current version
  • job: GitHub Release
    • if no release yet:
      • build locally
      • push with tag creation
  • job: PyPI release
    • if no PyPI release yet:
      • download distributive from GitHub releases
      • publish to PyPI

[andkononykhin]

addresses https://github.com/sicpa-dlab/didcomm-gemini/issues/48