Maintenance: Bump bootsnap from 1.9.3 to 1.9.4

Bumps [bootsnap](https://github.com/Shopify/bootsnap) from 1.9.3 to 1.9.4.
- [Release notes](https://github.com/Shopify/bootsnap/releases)
- [Changelog](https://github.com/Shopify/bootsnap/blob/master/CHANGELOG.md)
- [Commits](Shopify/bootsnap@v1.9.3...v1.9.4)

Gemfile.lock

@@ -121,7 +121,7 @@ GEM
     biz (1.8.2)
       clavius (~> 1.0)
       tzinfo
-    bootsnap (1.9.3)
+    bootsnap (1.9.4)
       msgpack (~> 1.0)
     brakeman (5.2.0)
     browser (5.3.1)