chore: Convert str.format to f-strings

[sellth]

Converted .format and % operator to f-strings where it improves readability and does not clash with the 100 character line length limit.

closes #116

[codecov]

Codecov Report

Attention: 22 lines in your changes are missing coverage. Please review.

Comparison is base (02f096d) 96.52% compared to head (fa8320d) 96.98%.
Report is 1 commits behind head on master.

Files	Patch %	Lines
altamisa/isatab/validate_assay_study.py	17.64%	14 Missing ⚠️
altamisa/apps/isatab2dot.py	83.33%	2 Missing ⚠️
altamisa/isatab/validate_investigation.py	89.47%	2 Missing ⚠️
altamisa/isatab/write_assay_study.py	0.00%	2 Missing ⚠️
tests/test_write_assay.py	66.66%	1 Missing ⚠️
tests/test_write_study.py	50.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #138      +/-   ##
==========================================
+ Coverage   96.52%   96.98%   +0.45%     
==========================================
  Files          29       29              
  Lines        3426     3380      -46     
==========================================
- Hits         3307     3278      -29     
+ Misses        119      102      -17     

Flag	Coverage Δ
python	96.98% <71.42%> (+0.45%)	⬆️

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[sellth]

Will move snapshot testing into separate PR to make reviewing easier.