Remove redundant whitespace (#5386)

.github/PULL_REQUEST_TEMPLATE.md

@@ -14,7 +14,7 @@ Add resource(s) | Remove resource(s) | Add info | Improve repo
 - [ ] Read our [contributing guidelines](https://github.com/EbookFoundation/free-programming-books/blob/master/CONTRIBUTING.md)
 - [ ] Search for duplicates.
 - [ ] Include author(s) and platform where appropriate.
-- [ ] Put lists  in alphabetical order, correct spacing.
+- [ ] Put lists in alphabetical order, correct spacing.
 - [ ] Add needed indications (PDF, access notes, under construction)
 
 ## Followup