Replace obsolete PCRE packages

pcre3 was removed from recent debian-based releases (eg. Trixie[1]),
while RHEL10/CentOS Stream 10 no longer ships pcre in favor of pcre2.

Use the latest whereto library release (0.5.0) which uses pcre2
instead.

[1] https://lists.debian.org/debian-devel/2021/11/msg00176.html

Depends-on: https://review.opendev.org/c/openstack/requirements/+/971428
Change-Id: Ibd5440bee268e20d6da574f1014d953cbb9e6620
Signed-off-by: Takashi Kajinami <kajinamit@oss.nttdata.com>

bindep.txt

@@ -8,4 +8,4 @@ python3-yaml [platform:ubuntu]
 git-review [platform:ubuntu]
 libre2-dev [platform:ubuntu]
 # This is for python-pcre which is a dependency of whereto.
-libpcre3-dev [platform:ubuntu]
+libpcre2-dev [platform:ubuntu]

doc/requirements.txt

@@ -3,7 +3,7 @@
 sphinx>=1.6.2  # BSD
 sphinxcontrib-datatemplates>=0.4.0  # BSD License
 icalendar>=3.10  # BSD
-whereto>=0.3.0  # Apache-2.0
+whereto>=0.5.0  # Apache-2.0
 mwclient==0.8.1
 yamlordereddictloader
 ruamel.yaml>=0.15

doc/source/conf.py

@@ -1,7 +1,6 @@
-# -*- coding: utf-8 -*-
-
 import datetime
 import os
+import subprocess
 import sys
 
 from sphinx.util import logging
@@ -64,8 +63,9 @@ html_static_path = ['static']
 # Output file base name for HTML help builder.
 htmlhelp_basename = '%sdoc' % project
 
-git_cmd = "git log --pretty=format:'%ad, commit %h' --date=local -n1"
-html_last_updated_fmt = os.popen(git_cmd).read()
+git_cmd = ["git", "log", "--pretty=format:'%ad, commit %h'", "--date=local", "-n1"]
+html_last_updated_fmt = subprocess.run(
+    git_cmd, capture_output=True, text=True, check=True).stdout
 
 # Grouping the document tree into LaTeX files. List of tuples
 # (source start file, target name, title, author, documentclass