feat: drop python 3.10 support (#2469)

# What does this PR do?

dropped python3.10, updated pyproject and dependencies, and also removed
some blocks of code with special handling for enum.StrEnum

Closes #2458

Signed-off-by: Charlie Doern <cdoern@redhat.com>

llama_stack/distribution/server/server.py

@@ -145,7 +145,7 @@ async def shutdown(app):
                 await asyncio.wait_for(impl.shutdown(), timeout=5)
             else:
                 logger.warning("No shutdown method for %s", impl_name)
-        except (asyncio.TimeoutError, TimeoutError):
+        except TimeoutError:
             logger.exception("Shutdown timeout for %s ", impl_name, exc_info=True)
         except (Exception, asyncio.CancelledError) as e:
             logger.exception("Failed to shutdown %s: %s", impl_name, {e})