Add environment variable to GitHub workflow

An environment variable, HTRC_NEXUS_DRHTRC_PWD, was added to the .github/workflows/dependency-graph.yml file. This variable was introduced to utilize GitHub secrets and it is part of the job 'dependency-graph'.

.github/workflows/dependency-graph.yml

@@ -3,6 +3,10 @@ on:
   push:
     branches:
       - main
+
+env:
+  HTRC_NEXUS_DRHTRC_PWD: ${{ secrets.HTRC_NEXUS_DRHTRC_PWD }}
+
 jobs:
   dependency-graph:
     name: Update Dependency Graph