ci: Fix error in the workflow. (#2159)

Author: bjohansebas

.github/workflows/update-external-docs.yml

@@ -27,7 +27,8 @@ jobs:
 
             - name: Bump Expires
               if: steps.expiry.outputs.bump == 'true'
-              run: sed -i "s/^Expires:.*/Expires: $(date -u -d '+180 days' +%Y-%m-%dT00:00:00Z)/I" .well-known/security.txt
+              run: |
+                  sed -i "s/^Expires:.*/Expires: $(date -u -d '+180 days' +%Y-%m-%dT00:00:00Z)/I" .well-known/security.txt
 
             - name: Create Pull Request
               if: steps.expiry.outputs.bump == 'true'