fix: Fix PR template (#517)

Fix PR template

Author: dbudziwojskiNR

.github/PULL_REQUEST_TEMPLATE.md

@@ -12,7 +12,7 @@
 ## Checklist:
 <!-- Please check applicable options. -->
 
-- [ ] Add changelog entry following the [contributing guide](../CONTRIBUTING.md#pull-requests)
+- [ ] Add changelog entry following the [contributing guide](https://github.com/newrelic/newrelic-prometheus-configurator/blob/main/CONTRIBUTING.md#pull-requests)
 - [ ] Documentation has been updated
 - [ ] This change requires changes in testing:
   - [ ] unit tests