Fix broken connection to netfilter.org which refuse connection without the header.

DEBUG: loading config file at: /home/seblu/.config/archversion/packages.conf
DEBUG: Loading database /home/seblu/.cache/archversion/packages.cache
DEBUG: Syncing versions of package libnftnl
DEBUG: Get upstream version
DEBUG: Requesting url: https://www.netfilter.org/projects/libnftnl/files/ (try 1/4)
DEBUG: Timeout is 30.0
DEBUG: Requesting url: https://www.netfilter.org/projects/libnftnl/files/ (try 2/4)
DEBUG: Timeout is 30.0
DEBUG: Requesting url: https://www.netfilter.org/projects/libnftnl/files/ (try 3/4)
DEBUG: Timeout is 30.0
DEBUG: Requesting url: https://www.netfilter.org/projects/libnftnl/files/ (try 4/4)
DEBUG: Timeout is 30.0
ERROR: Sync of libnftnl: Upstream check failed: HTTP Error 403: Forbidden
DEBUG: Comparing versions of package libnftnl

Fix commit count in pkgver
Use date in pkgver

Use re.search instead of re.match

Some web sites have buggy utf8 encoding or not use utf8.
We don't have to be strict, we want a wide coverage.

A bug was introduced by sorting the cache content. Resulting of destroying
the cache object and replace it with a simple dict with no saving.

- Support upgrade
- Refactorise code

python modules have been splitted out from systemd main git tree

Since last major update, a package failure stops the whole sync.
If a package check fails, skip it

Instead of an int vs str error