Bump bootsnap from 1.4.1 to 1.4.3 (#245)

Bumps [bootsnap](https://github.com/Shopify/bootsnap) from 1.4.1 to 1.4.3.
- [Release notes](https://github.com/Shopify/bootsnap/releases)
- [Changelog](https://github.com/Shopify/bootsnap/blob/master/CHANGELOG.md)
- [Commits](https://github.com/Shopify/bootsnap/compare/v1.4.1...v1.4.3)

Signed-off-by: dependabot[bot] <support@dependabot.com>

Gemfile.lock

@@ -75,7 +75,7 @@ GEM
     aws-sigv4 (1.0.1)
     bcrypt (3.1.12)
     bindex (0.5.0)
-    bootsnap (1.4.1)
+    bootsnap (1.4.3)
       msgpack (~> 1.0)
     bootstrap (4.1.3)
       autoprefixer-rails (>= 6.0.3)
@@ -199,7 +199,7 @@ GEM
       minitest-rails (~> 3.0)
     mocha (1.8.0)
       metaclass (~> 0.0.1)
-    msgpack (1.2.6)
+    msgpack (1.2.9)
     nio4r (2.3.1)
     nokogiri (1.10.2)
       mini_portile2 (~> 2.4.0)