Improve coverage

[marcelofern]

By adding pragma no covers in "NoImplementedError" code paths and also by removing unused code.

[github-actions]

Coverage Report Results

Name	Stmts	Miss	Branch	BrPart	Cover
src/psycopack/__init__.py	9	0	0	0	100%
src/psycopack/_commands.py	187	0	24	0	100%
src/psycopack/_conn.py	5	0	0	0	100%
src/psycopack/_const.py	3	0	0	0	100%
src/psycopack/_cur.py	24	0	2	0	100%
src/psycopack/_identifiers.py	12	0	2	0	100%
src/psycopack/_introspect.py	199	0	20	0	100%
src/psycopack/_logging.py	2	0	0	0	100%
src/psycopack/_partition.py	13	0	0	0	100%
src/psycopack/_psycopg.py	5	0	0	0	100%
src/psycopack/_registry.py	88	0	12	0	100%
src/psycopack/_repack.py	466	2	172	5	99%
src/psycopack/_sync_strategy.py	4	0	0	0	100%
src/psycopack/_tracker.py	180	0	42	0	100%
tests/conftest.py	19	0	0	0	100%
tests/factories.py	41	0	10	0	100%
tests/test_cur.py	20	0	2	0	100%
tests/test_fixtures.py	5	0	0	0	100%
tests/test_package.py	3	0	0	0	100%
tests/test_repack.py	1071	0	20	0	100%
TOTAL	2356	2	306	5	99%

1 empty file skipped.