src/robots.txt.ejs: remove blank line

According to the notes on the DSpace 7 wiki we cannot have blank
lines.

See: https://wiki.lyrasis.org/display/DSDOC7x/Search+Engine+Optimization

src/robots.txt.ejs

@@ -16,7 +16,6 @@ Disallow: /submit
 Disallow: /workspaceitems
 Disallow: /profile
 Disallow: /workflowitems
-
 # Optionally uncomment the following line ONLY if sitemaps are working
 # and you have verified that your site is being indexed correctly.
 Disallow: /browse/*