Drop Python 3.6 & 3.7

[mr-c]

No description provided.

[codecov]

Codecov Report

Merging #241 (d674e4d) into main (139c64b) will decrease coverage by 0.01%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main     #241      +/-   ##
==========================================
- Coverage   40.93%   40.93%   -0.01%     
==========================================
  Files          30       30              
  Lines       23530    23528       -2     
  Branches     6659     6390     -269     
==========================================
- Hits         9633     9631       -2     
  Misses      11822    11822              
  Partials     2075     2075              

Files Changed	Coverage Δ
cwl_utils/sandboxjs.py	59.41% <ø> (ø)
cwl_utils/singularity.py	61.90% <ø> (ø)
cwl_utils/expression.py	53.75% <100.00%> (-0.27%)	⬇️
cwl_utils/parser/cwl_v1_2_utils.py	78.85% <100.00%> (-0.08%)	⬇️