remove browserstack image for now [skip ci]
remove browserstack image for now [skip ci]

nathandunn/jbrowse,GMOD/jbrowse,GMOD/jbrowse,nathandunn/jbrowse,nathandunn/jbrowse,GMOD/jbrowse,nathandunn/jbrowse,GMOD/jbrowse,GMOD/jbrowse,nathandunn/jbrowse