fix message for selecting custom formatter

src/formatters/custom.rs

@@ -114,6 +114,8 @@ where
 mod tests {
     use crate::config::Config;
 
+    use pretty_assertions::assert_str_eq;
+
     use super::*;
 
     #[test]
@@ -158,7 +160,7 @@ t config --formatter-search-paths <path>..");
         });
         let err = print_formatted("pollo", Vec::new(), &mut out, &mut err, &facts).unwrap_err();
 
-        assert_eq!(err.to_string(), "\
+        assert_str_eq!(err.to_string(), "\
 Could not find a formatter with name 'pollo' in any of the following paths:
 
     - /not/a/path
@@ -168,6 +170,6 @@ which where taken from your config file located at
 
     /etc/tiempo/config.toml
 
-Perhaps is mispelled?");
+Perhaps it is mispelled?");
     }
 }