Removed broken Travis build badge

Author: davidcsterratt

README.md

@@ -73,14 +73,8 @@ improvements (released in v0.7.0) were supported by an NIH R21 grant
 (EY027894) from 2018-2020 to Dr. Mark P. Krebs, The Jackson
 Laboratory.
 
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-[![Travis build status](https://travis-ci.com/davidcsterratt/retistruct.svg?branch=master)](https://travis-ci.com/davidcsterratt/retistruct)
-<!-- badges: end -->
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 <!--  LocalWords:  Retistruct Github CRAN devtools davidcsterratt EY
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 <!--  LocalWords:  subdir retistruct Roadmap Wellcome Harbor retinae
 <!--  LocalWords:  devtoools
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