fix: resolve mypy divergence between make check and pre-commit

- Add tenacity>=8.2 to pre-commit mypy additional_dependencies
- Remove now-unnecessary type: ignore comment from pubmed.py

Root cause: pre-commit mypy was missing tenacity, so it couldn't
resolve the

@retry
decorator's type signature.

.pre-commit-config.yaml

@@ -14,4 +14,5 @@ repos:
         additional_dependencies:
           - pydantic>=2.7
           - pydantic-settings>=2.2
+          - tenacity>=8.2
         args: [--ignore-missing-imports]

src/tools/pubmed.py

@@ -42,7 +42,7 @@ class PubMedTool:
             params["api_key"] = self.api_key
         return params
 
-    @retry(  # type: ignore[misc]
+    @retry(
         stop=stop_after_attempt(3),
         wait=wait_exponential(multiplier=1, min=1, max=10),
         reraise=True,