Adjust gcc_release for id href web transformations

Adjust gcc_release for id href web transformations

We now have some script which transforms e.g.
<h2 id="15.1">GCC 15.1</h2>
line in gcc-15/changes.html to
<h2 id="15.1"><a href="#15.1">GCC 15.1</a></h2>

This unfortunately breaks the gcc_release script, which looks for
GCC 15.1 appearing in gennews after optional blanks from the start of
the line in the NEWS file, which is no longer the case, there is
[129]GCC 15.1
or something like that with an URL later on
 129. https://gcc.gnu.org/gcc-15/changes.html#15.1

The following patch handles this.

2025-04-25  Jakub Jelinek  <jakub@redhat.com>

	* gcc_release: Allow optional \[[0-9]+\] before GCC major.minor
	in the NEWS file.

(cherry picked from commit fef3a3c8b5d35c7a8eeae67f95a264a90120dd29)