[FIX] add extensions in fnames for filewrite

[emdupre]

Changes proposed in this pull request:

• Adds extensions for filenames written by utils.filewrite()
• Patches CI testing

[codecov]

Codecov Report

Merging #92 into master will not change coverage.
The diff coverage is 0%.

@@           Coverage Diff           @@
##           master      #92   +/-   ##
=======================================
  Coverage   27.95%   27.95%           
=======================================
  Files          25       25           
  Lines        1381     1381           
=======================================
  Hits          386      386           
  Misses        995      995

Impacted Files	Coverage Δ
tedana/workflows/tedana.py	0% <0%> (ø)	⬆️

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