Update pull_request_template.md

.github/pull_request_template.md

@@ -4,7 +4,7 @@ Thank you for contributing to capa! <3
 
 Please ensure that:
 1. each rule passes thorough linting (in rules directory: `python ../scripts/lint.py --thorough -t "<your rule name>" -v .`)
-2. you've uploaded each referenced example binary (optional, but greatly appreciated) to https://github.com/fireeye/capa-testfiles
+2. you've uploaded each referenced example binary (optional, but greatly appreciated) to https://github.com/mandiant/capa-testfiles
 
 Please mention the issue your PR addresses (if any):
 closes #issue_number