Add write permissions for coverage on pull requests

[Bouni]

I hope this fixes the last issue in #151

[github-actions]

Coverage Report

File	Stmts	Miss	Cover	Missing
luxtronik
__init__.py	143	110	23%	39–55, 62–67, 70, 74–79, 84–88, 101–104, 111, 115, 119, 123, 134, 137–140, 143–163, 166–181, 184–201, 204–219, 223–225, 229–230, 234–235
__main__.py	21	21	0%	3–49
datatypes.py	275	12	96%	38, 43, 48, 58, 73–76, 81–84, 93
discover.py	43	34	21%	26–78
luxtronik/scripts
dump_changes.py	44	44	0%	5–93
dump_luxtronik.py	28	28	0%	5–64
TOTAL	637	249	61%

Tests	Skipped	Failures	Errors	Time
116	4 💤	0 ❌	0 🔥	0.651s ⏱️

[Bouni]

OK, this indeed fixes the coverage problem you have noticed in #151
After merging this, rebase #151 and we should be back on track

[gerw]

Ok, lets try!