fix: remove incorrect back tics in CONTRIBUTING.md

Author: gr2m

lib/create-contributing.js

@@ -49,7 +49,7 @@ npm test
 You can install \`${packageName}\` from each pull request. Replace \`[PULL REQUEST NUMBER]\`:
 
 \`\`\`
-npm install https://github.pika.dev/\`${owner}/${repo}\`/pr/[PULL REQUEST NUMBER]
+npm install https://github.pika.dev/${owner}/${repo}/pr/[PULL REQUEST NUMBER]
 \`\`\`
 
 Once you are done testing, you can revert back to the default module \`${packageName}\` from npm with \`npm install ${packageName}\`