Change platform name for EPIC (DSCOVR) to upper case.

[simonrp84]

In a recent pyspectral PR I added spectral response functions for EPIC. @adybbroe mentioned that the platform name in that PR should be upper case. The same is true in satpy, so here I make a PR to correct the platform name to the WMO standard name.

[codecov]

Codecov Report

Merging #2606 (58ddfaa) into main (34e2bd9) will not change coverage.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##             main    #2606   +/-   ##
=======================================
  Coverage   94.94%   94.94%           
=======================================
  Files         354      354           
  Lines       51474    51474           
=======================================
  Hits        48873    48873           
  Misses       2601     2601           

Flag	Coverage Δ
behaviourtests	4.27% <0.00%> (ø)
unittests	95.56% <100.00%> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Files	Coverage Δ
satpy/readers/epic_l1b_h5.py	100.00% <100.00%> (ø)
satpy/tests/writer_tests/test_cf.py	95.53% <ø> (ø)

[coveralls]

Pull Request Test Coverage Report for Build 6589533562

• 1 of 1 (100.0%) changed or added relevant line in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 95.514%

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Totals
Change from base Build 6550698316:	0.0%
Covered Lines:	48996
Relevant Lines:	51297

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💛 - Coveralls