Lock vue-loader to 15.9.8 to fix build issues (#4653)

* Use a fixed version number for vue-loader to avoid a webpack build issue in some system configurations

* Ask dependabot to keep an eye out for vue-loader updates

Co-authored-by: John Hill <john.c.hill@nasa.gov>

.github/dependabot.yml

@@ -16,6 +16,7 @@ updates:
       - dependency-name: "*jasmine*"
       - dependency-name: "*playwright*"
       - dependency-name: "*percy*"
+      - dependency-name: "*vue-loader*"
 
   - package-ecosystem: "github-actions"
     directory: "/"

package.json

@@ -74,7 +74,7 @@
     "v8-compile-cache": "^1.1.0",
     "vue": "2.5.6",
     "vue-eslint-parser": "8.0.1",
-    "vue-loader": "^15.2.6",
+    "vue-loader": "15.9.8",
     "vue-template-compiler": "2.5.6",
     "webpack": "^5.53.0",
     "webpack-cli": "^4.0.0",