Add codecov secret to test on PR GitHub CI workflow - expect to see coverage info (#133)

* Use add codecov secret to test on pr

* Fix codecov syntax yaml

* Use the existing CODECOV_TOKEN yaml syntax

* Add news for codecov in PR

* Run CI with empty commit

Author: bobleesj

.github/workflows/tests-on-pr.yml

@@ -14,3 +14,5 @@ jobs:
       project: diffpy.snmf
       c_extension: false
       headless: false
+    secrets:
+      CODECOV_TOKEN: ${{ secrets.CODECOV_TOKEN }}

news/codecov.rst

@@ -0,0 +1,23 @@
+**Added:**
+
+* Codecov coverage report in PR
+
+**Changed:**
+
+* <news item>
+
+**Deprecated:**
+
+* <news item>
+
+**Removed:**
+
+* <news item>
+
+**Fixed:**
+
+* <news item>
+
+**Security:**
+
+* <news item>