chore: Set pytest-asyncio as a dev dependency (#250)

We are only using `pytest-asyncio` in the tests and it can break
compatibility with `pytest-mergify` if the user is not using the
appropriate version of `pytest-asyncio`.

Author: remyduthu

poetry.lock

@@ -13,9 +13,6 @@ opentelemetry-exporter-otlp-proto-http = ">=1.29"
 opentelemetry-sdk = ">=1.29"
 requests = ">=2"
 pytest = ">=6.0.0"
-# https://github.com/pytest-dev/pytest-asyncio/issues/706#issuecomment-2082788963
-pytest-asyncio = "0.24.0"
-
 
 [tool.poetry.group.dev.dependencies]
 ruff = ">=0.12,<0.15.0"
@@ -25,6 +22,8 @@ codespell = "^2.3.0"
 yamllint = "^1.35.1"
 anys = "^0.3.1"
 responses = "^0.25.7"
+# https://github.com/pytest-dev/pytest-asyncio/issues/706#issuecomment-2082788963
+pytest-asyncio = "0.21.2"
 
 [build-system]
 requires = ["poetry-core", "poetry-dynamic-versioning"]