CI: fix benchmark steps, disable dependency caching

[wpbonelli]

Fixes multiline command syntax error in Windows benchmark job. Also disables dependency caching (pip, conda and modflow executables) pending resolution of GitHub actions hashFiles() timeouts.

[codecov]

Codecov Report

Merging #1494 (eadc8b3) into develop (3b8eedb) will decrease coverage by 42.548%.
The diff coverage is n/a.

❗ Current head eadc8b3 differs from pull request most recent head f40ecdb. Consider uploading reports for the commit f40ecdb to get more accurate results

@@              Coverage Diff               @@
##           develop     #1494        +/-   ##
==============================================
- Coverage   72.489%   29.941%   -42.549%     
==============================================
  Files          250       250                
  Lines        54002     52532      -1470     
==============================================
- Hits         39146     15729     -23417     
- Misses       14856     36803     +21947     

Impacted Files	Coverage Δ
flopy/mfusg/mfusgsms.py	6.190% <0.000%> (-91.941%)	⬇️
flopy/mf6/utils/postprocessing.py	9.259% <0.000%> (-88.889%)	⬇️
flopy/seawat/swtvdf.py	8.092% <0.000%> (-88.460%)	⬇️
flopy/modflow/mfevt.py	7.537% <0.000%> (-87.463%)	⬇️
flopy/utils/mtlistfile.py	4.620% <0.000%> (-85.348%)	⬇️
flopy/mf6/utils/lakpak_utils.py	2.097% <0.000%> (-85.315%)	⬇️
flopy/modflow/mfhyd.py	13.223% <0.000%> (-85.124%)	⬇️
flopy/utils/swroutputfile.py	10.714% <0.000%> (-85.079%)	⬇️
flopy/modflow/mfag.py	7.282% <0.000%> (-83.878%)	⬇️
flopy/modflow/mfhob.py	5.923% <0.000%> (-83.005%)	⬇️
... and 205 more