[pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

Author: pre-commit-ci[bot]

source/guides/handling-missing-extras-at-runtime.rst

@@ -63,4 +63,3 @@ Unfortunately, no replacement for this functionality exists in the
 ------------------
 
 .. _packaging-problems-664: https://github.com/pypa/packaging-problems/issues/664
-