Merge pull request #672 from ohbarye/dependabot/bundler/backend/bootsnap-1.9.4

Bump bootsnap from 1.9.3 to 1.9.4 in /backend

Author: ohbarye

backend/Gemfile.lock

@@ -63,7 +63,7 @@ GEM
     addressable (2.8.0)
       public_suffix (>= 2.0.2, < 5.0)
     bindex (0.8.1)
-    bootsnap (1.9.3)
+    bootsnap (1.9.4)
       msgpack (~> 1.0)
     builder (3.2.4)
     byebug (11.1.3)