Replace pkg_resources usage with importlib.metadata.

[nuclearsandwich]

pkg_resources is only used to fetch and provide the current superflore version.

In fact, there's very little need to parse this version at all (which would also require adding the packaging module as a dependency. Instead of parsing the version for the test, I used a cursed regexp that will test the value is greater than the current release when present.

Resolves #314.

[nuclearsandwich]

This convoluted indirection was an attempt to work around local import trouble with the RepoInstance. It may be we don't need the superflore.version module if the tests are better behaved in general than they are in my local workspace.

[robwoolley]

Unfortunately, the unit tests aren't well behaved. They don't cover OpenEmbedded and the Gentoo support is working but showing it's age.

I did run the following as a test:
sed -i "s/lunar/noetic/g" tests/test_ebuild.py tests/test_generate_installers.py tests/ebuild/simple_expected.ebuild

python -m unittest tests.test_ebuild
python -m unittest tests.test_generate_installers

as well as this to do some limited testing on the new version changes:
python -m unittest tests.test_utils

This seems sufficient for now.

[robwoolley]

Thanks @nuclearsandwich for tackling this.

It seems that the new lines have a new Flake8 error:

superflore/utils.py:29:1: I100 Import statements are in the wrong order. 'from superflore.exceptions import UnknownPlatform' should be before 'from superflore.version import VERSION'
superflore/utils.py:29:1: I202 Additional newline in a group of imports. 'from superflore.exceptions import UnknownPlatform' is identified as Third Party and 'from superflore.version import VERSION' is identified as Third Party.
superflore/version.py:11:1: W391 blank line at end of file

It seemed to be happy with this modification:

git diff superflore/utils.py
diff --git a/superflore/utils.py b/superflore/utils.py
index b549beb..b19500d 100644
--- a/superflore/utils.py
+++ b/superflore/utils.py
@@ -24,10 +24,9 @@ import time
 from typing import Dict
 import urllib.request

-from superflore.version import VERSION
-
 from superflore.exceptions import UnknownPlatform
 from superflore.rosdep_support import get_cached_index, resolve_rosdep_key
+from superflore.version import VERSION
 from termcolor import colored

In addition to removing the extra line at the end of version.py.

[robwoolley]

Unfortunately, the unit tests aren't well behaved. They don't cover OpenEmbedded and the Gentoo support is working but showing it's age.

I did run the following as a test:
sed -i "s/lunar/noetic/g" tests/test_ebuild.py tests/test_generate_installers.py tests/ebuild/simple_expected.ebuild

python -m unittest tests.test_ebuild
python -m unittest tests.test_generate_installers

as well as this to do some limited testing on the new version changes:
python -m unittest tests.test_utils

This seems sufficient for now.

[nuclearsandwich]

Surprised (and a little disappointed) that my use of a cursed regexp to do the version parsing went unremarked.

[robwoolley]

https://xkcd.com/208/