Bump simple_form from 3.5.0 to 4.0.0

Bumps [simple_form](https://github.com/plataformatec/simple_form) from 3.5.0 to 4.0.0.
- [Release notes](https://github.com/plataformatec/simple_form/releases)
- [Changelog](https://github.com/plataformatec/simple_form/blob/master/CHANGELOG.md)
- [Commits](heartcombo/simple_form@v3.5.0...v4.0.0)

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

Author: dependabot-support

Gemfile.lock

@@ -364,9 +364,9 @@ GEM
       tilt (>= 1.1, < 3)
     shoulda-matchers (3.1.2)
       activesupport (>= 4.0.0)
-    simple_form (3.5.0)
-      actionpack (> 4, < 5.2)
-      activemodel (> 4, < 5.2)
+    simple_form (4.0.0)
+      actionpack (> 4)
+      activemodel (> 4)
     simplecov (0.12.0)
       docile (~> 1.1.0)
       json (>= 1.8, < 3)