Fix links with extra trailing characters (Closes: #994897)

Proper URL validation is pretty complex, so we're only adding an heuristic against common issues (sentence-closing period or parenthesis without space right after an URL).

Examples:

• CVE-2019-11841: "See https://github.com/golang/go/issues/41200."
• CVE-2025-3576: "(cf. https://web.mit.edu/kerberos/krb5-1.21/)"
• CVE-2024-36462: "in https://github.com/.../036f3e14be3, first"
• CVE-2024-27280: "bugfix for https://bugs.ruby-lang.org/issues/19389:"
• CVE-2009-0676: "in https://bugzilla.redhat.com/show_bug.cgi?id=486305"

False-positives analysis:

• '.,:' technically valid in URLs, but no valid occurrences in the tracker;
• ')>' should be URL-encoded in the non-hostname part of the URL.