doctest: fix type of DocTestParser.get_doctest(lineno) (#3206)

Reference:
https://docs.python.org/3/library/doctest.html#doctest.DocTest.lineno

Also noticed a typo in get_examples() argument name.

Author: bluetech

stdlib/2and3/doctest.pyi

@@ -56,8 +56,8 @@ class DocTest:
 
 class DocTestParser:
     def parse(self, string: str, name: str = ...) -> List[Union[str, Example]]: ...
-    def get_doctest(self, string: str, globs: Dict[str, Any], name: str, filename: Optional[str], lineno: Optional[str]) -> DocTest: ...
-    def get_examples(self, strin: str, name: str = ...) -> List[Example]: ...
+    def get_doctest(self, string: str, globs: Dict[str, Any], name: str, filename: Optional[str], lineno: Optional[int]) -> DocTest: ...
+    def get_examples(self, string: str, name: str = ...) -> List[Example]: ...
 
 class DocTestFinder:
     def __init__(self, verbose: bool = ..., parser: DocTestParser = ...,