Bump rack from 1.6.11 to 1.6.13

Bumps [rack](https://github.com/rack/rack) from 1.6.11 to 1.6.13.
- [Release notes](https://github.com/rack/rack/releases)
- [Changelog](https://github.com/rack/rack/blob/master/CHANGELOG.md)
- [Commits](rack/rack@1.6.11...1.6.13)

---
updated-dependencies:
- dependency-name: rack
  dependency-type: indirect
...

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

Author: dependabot[bot]

Gemfile.lock

@@ -1,12 +1,11 @@
 GIT
-  remote: https://github.com/Compass/compass-rails.git
-  revision: 3e88f991150ffa39b0a539dffb3326248d18e6ad
-  branch: master
+  remote: https://github.com/Compass/compass-rails
+  revision: f6391d0d30fa63bb9bf6cd94e0e5608012584e6e
   specs:
-    compass-rails (2.0.4)
+    compass-rails (4.0.0)
       compass (~> 1.0.0)
       sass-rails (< 5.1)
-      sprockets (< 2.13)
+      sprockets (< 4.0)
 
 GIT
   remote: https://github.com/ko1/debugger2.git
@@ -17,7 +16,7 @@ GIT
       debugger-linecache (~> 1.2.0)
 
 GIT
-  remote: https://github.com/naaano/active_scaffold_export.git
+  remote: https://github.com/naaano/active_scaffold_export
   revision: 879ceb549b871ebb597ae5339a2e67498beb70d1
   specs:
     active_scaffold_export (3.3.2)
@@ -83,7 +82,7 @@ GEM
       compass-rails (>= 2.0.4)
       railties (>= 3.0)
       sass-rails (>= 3.2)
-    chunky_png (1.3.4)
+    chunky_png (1.4.0)
     climate_control (0.0.3)
       activesupport (>= 3.0)
     cocaine (0.5.7)
@@ -122,7 +121,7 @@ GEM
     erubi (1.9.0)
     erubis (2.7.0)
     execjs (2.5.2)
-    ffi (1.9.8)
+    ffi (1.15.5)
     foundation-rails (5.5.2.1)
       railties (>= 3.1.0)
       sass (>= 3.3.0, < 3.5)
@@ -207,7 +206,7 @@ GEM
       pry (>= 0.10.4)
     quiet_assets (1.1.0)
       railties (>= 3.1, < 5.0)
-    rack (1.6.11)
+    rack (1.6.13)
     rack-cors (1.0.3)
     rack-test (0.6.3)
       rack (>= 1.0)
@@ -243,9 +242,9 @@ GEM
       thor (>= 0.18.1, < 2.0)
     rainbow (3.0.0)
     rake (13.0.0)
-    rb-fsevent (0.9.5)
-    rb-inotify (0.9.5)
-      ffi (>= 0.5.0)
+    rb-fsevent (0.11.1)
+    rb-inotify (0.10.1)
+      ffi (~> 1.0)
     rsolr (1.0.12)
       builder (>= 2.1.2)
     rubocop (0.75.1)