Migrate to UV (#1748)

* Switch to using `uv` for dependency management and update related project workflows and scripts

* Expand contributing documentation with instructions for using `uv`, including dependency management, testing, linting, and docs workflows.

* Add changelog entry for migration to `uv` for dependency management and workflows

aiogram/dispatcher/dispatcher.py

@@ -679,6 +679,6 @@ class Dispatcher(Router):
                 if sys.version_info >= (3, 11):
                     with asyncio.Runner(loop_factory=uvloop.new_event_loop) as runner:
                         return runner.run(coro)
-                else:
+                else:  # pragma: no cover
                     uvloop.install()
                     return asyncio.run(coro)