[DOC] Updates copyright year

[jbteves]

Closes #289 .

Changes proposed in this pull request:

• Changes copyright year max to 2019

[tsalo]

LGTM.

[codecov]

Codecov Report

Merging #291 into master will decrease coverage by 0.22%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #291      +/-   ##
==========================================
- Coverage   46.16%   45.94%   -0.23%     
==========================================
  Files          35       35              
  Lines        2060     2070      +10     
==========================================
  Hits          951      951              
- Misses       1109     1119      +10

Impacted Files	Coverage Δ
tedana/workflows/tedana.py	12.43% <0%> (-0.72%)	⬇️

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