Updated cartopy terrain reference and changed to requirements.txt

[ssuffian]

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Description

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[codecov[bot]]

Codecov Report

:exclamation: No coverage uploaded for pull request base (master@99923d8). Click here to learn what that means. The diff coverage is 100%.

@@           Coverage Diff           @@
##             master    #49   +/-   ##
=======================================
  Coverage          ?   100%           
=======================================
  Files             ?     32           
  Lines             ?   2650           
  Branches          ?      0           
=======================================
  Hits              ?   2650           
  Misses            ?      0           
  Partials          ?      0

Impacted Files	Coverage Δ
eeweather/visualization.py	100% <ø> (ø)
tests/snapshots/snap_test_ranking.py	100% <100%> (ø)

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