style: add a couple rules to ruff

[tlambert03]

among others, bans relative imports

[codecov]

Codecov Report

Patch coverage: 100.00% and project coverage change: -0.01 ⚠️

Comparison is base (de02308) 96.33% compared to head (c2f3ca7) 96.32%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #103      +/-   ##
==========================================
- Coverage   96.33%   96.32%   -0.01%     
==========================================
  Files          12       12              
  Lines         736      735       -1     
==========================================
- Hits          709      708       -1     
  Misses         27       27              

Impacted Files	Coverage Δ
src/useq/__init__.py	100.00% <100.00%> (ø)
src/useq/_actions.py	100.00% <100.00%> (ø)
src/useq/_channel.py	96.29% <100.00%> (ø)
src/useq/_hardware_autofocus.py	96.96% <100.00%> (ø)
src/useq/_mda_event.py	86.20% <100.00%> (-0.24%)	⬇️
src/useq/_mda_sequence.py	98.34% <100.00%> (ø)
src/useq/_position.py	96.00% <100.00%> (ø)
src/useq/_time.py	100.00% <100.00%> (ø)
src/useq/_z.py	98.38% <100.00%> (ø)

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