Fix typo

pyproject.toml

@@ -2,7 +2,7 @@
 name = "requests-http-message-signatures"
 version = "0.3.0-dev1"
 description = "A request authentication plugin implementing IETF HTTP Message Signatures"
-readme = "README.rst"
+readme = "README.md"
 homepage = "https://dev.funkwhale.audio/funkwhale/requests-http-message-signatures"
 license = "Apache-2.0"
 authors = ["Andrey Kislyuk", "Funkwhale Collective <maintainers@funkwhale.audio>"]
@@ -26,6 +26,7 @@ requests = "^2"
 
 [tool.poetry.dev-dependencies]
 Sphinx = "^4.5.0"
+coverage = "^6.3.2"
 
 [build-system]
 requires = ["poetry-core>=1.0.0"]