fix: lint

Author: RanKKI

Misc/NEWS.d/next/Library/2024-10-24-10-49-47.gh-issue-124452.eqTRgx.rst

@@ -1,4 +1,4 @@
 Fix an issue in :meth:`email.policy.EmailPolicy.header_source_parse` and
 :meth:`email.policy.Compat32.header_source_parse` that introduced spurious
 leading whitespaces into header values when the header includes a newline
-character after the header name delimiter (`:`) and before the value.
+character after the header name delimiter (``:``) and before the value.