Remove unused comment field of gitea.lemnoslife.com/Benjamin_Loison/LemnosLife_Rust

It's a real debate whether or not to include the field with empty string
to equivalently mean that there isn't any specific comment that the
author wanted to share. To minimize file sizes and improve readability
let's proceed by not specifying default values to fields.

repositories/gitea.lemnoslife.com/Benjamin_Loison/LemnosLife_Rust.json

@@ -1,4 +1,3 @@
 {
-    "commit": "657579086a1abcb4d859eb1ee30fc36e75504018",
-    "comment": ""
+    "commit": "657579086a1abcb4d859eb1ee30fc36e75504018"
 }