fix(.gitattributes): enforce unix line endings for data files (#154)

Co-authored-by: Eric Morway <emorway@usgs.gov>

.gitattributes

@@ -13,3 +13,7 @@
 *.png binary
 *.jpg binary
 *.pdf binary
+
+# Later lines modify earlier lines
+data/** text eol=lf
+data/**/*.tif binary