Update CHANGELOG for Git PR number

CHANGELOG.rst

@@ -24,7 +24,7 @@ number of the code change for that issue.  These PRs can be viewed at:
   the computation for rejecting catalog creation based on expected cosmic ray
   detections to fail ONLY for WFPC2.  Also, updated the WFPC2 cr_residual factor
   from 0.0 to 0.05 as it had never be set correctly.  Created a PyTest for
-  WFPC2 SVM processing. [#nnnn]
+  WFPC2 SVM processing. [#1969]
 
 - Updated the Pyproject.toml file to force use of Photutils v2.0.0 or greater.
   This update is in support of the change addressed by #1950. [#1966]