feat: throw an Error if package.json has duplicate "repository" key (#1656)

lib/definitions/errors.js

@@ -29,6 +29,10 @@ Please make sure to add the \`repositoryUrl\` to the [semantic-release configura
       'docs/usage/configuration.md'
     )}).`,
   }),
+  EDUPLICATEREPOSITORYKEY: ({packageJsonPath}) => ({
+    message: 'Duplicate `"repository"` key in package.json.',
+    details: `Your package.json file at ${packageJsonPath} has more than one "repository" keys.`,
+  }),
   EGITNOPERMISSION: ({options: {repositoryUrl}, branch: {name}}) => ({
     message: 'Cannot push to the Git repository.',
     details: `**semantic-release** cannot push the version tag to the branch \`${name}\` on the remote Git repository with URL \`${repositoryUrl}\`.