Fix release job's condition

Fix release job's condition

Fix memoisation of lazy parser & bump version

Reported by @Rafiot: the lazy parser is not memoised, this has limited
effect on the basic / pure Python parser as its initialisation is
trivial, but it *significantly* impact the re2 and regex parsers as
they need to process regexes into a filter tree.

The memoization was mistakenly removed in #230: while refactoring
initialisation I removed the setting of the `parser` global.

- add a test to ensure the parser is correctly memoized, not
  re-instantiated every time
- reinstate setting the global
- add a mutex on `__getattr__`, it should only be used on first access
  and avoids two threads creating an expensive parser at the same
  time (which is a waste of CPU)

Fixes #253

Update version to 1.0

Hopefully I've not missed one hidden somewhere.

Also update the development status because y not.

Closes #234

Fix a bunch of URLs

- it's pypi.org not pypy.org
- rtfd doesn't serve docs out of its main domain (which makes sense
  since docs can contain arbitrary JS)
- add the doc and issues to the project URLs

Add doc badges, link action badge

Slightly late update of uap-core to 0.18.0

See ua-parser/uap-core@v0.16.0...v0.18.0
for the upstream changelog

Also remove 2.7 and 3.6 from the changelog as they're not accessible
from setup-python anymore, we'd need to e.g. install them by hand
using pyenv if we want to keep them (which might be a good idea but
it's not like anyone is touching the 0.x code so changes of breakage
are low anyway).

- actions/setup-python#672
- actions/setup-python#544

Release 0.16.1

Fixes concurrency issues with the cache invalidation mechanism.

Release 0.15.2

Fix for #132 on 0.15

Update uap-core to 0.16.0

Closes #129