Bump middleman-autoprefixer from 2.9.0 to 2.10.0

Bumps [middleman-autoprefixer](https://github.com/middleman/middleman-autoprefixer) from 2.9.0 to 2.10.0.
- [Release notes](https://github.com/middleman/middleman-autoprefixer/releases)
- [Changelog](https://github.com/middleman/middleman-autoprefixer/blob/master/CHANGELOG.md)
- [Commits](middleman/middleman-autoprefixer@v2.9.0...v2.10.0)

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

Gemfile.lock

@@ -1,16 +1,16 @@
 GEM
   remote: https://rubygems.org/
   specs:
-    activesupport (5.0.6)
+    activesupport (5.0.7.1)
       concurrent-ruby (~> 1.0, >= 1.0.2)
-      i18n (~> 0.7)
+      i18n (>= 0.7, < 2)
       minitest (~> 5.1)
       tzinfo (~> 1.1)
     addressable (2.5.2)
       public_suffix (>= 2.0.2, < 4.0)
-    autoprefixer-rails (8.0.0)
+    autoprefixer-rails (9.4.5)
       execjs
-    backports (3.11.1)
+    backports (3.11.4)
     bourbon (5.1.0)
       sass (~> 3.4)
       thor (~> 0.19)
@@ -21,23 +21,23 @@ GEM
     coffee-script-source (1.12.2)
     compass-import-once (1.0.5)
       sass (>= 3.2, < 3.5)
-    concurrent-ruby (1.0.5)
+    concurrent-ruby (1.1.4)
     contracts (0.13.0)
-    dotenv (2.2.1)
+    dotenv (2.6.0)
     em-websocket (0.5.1)
       eventmachine (>= 0.12.9)
       http_parser.rb (~> 0.6.0)
     erubis (2.7.0)
     eventmachine (1.2.0.1)
     execjs (2.7.0)
     fast_blank (1.0.0)
-    fastimage (2.1.1)
+    fastimage (2.1.5)
     ffi (1.9.25)
     haml (4.0.7)
       tilt
     hamster (3.0.0)
       concurrent-ruby (~> 1.0)
-    hashie (3.5.7)
+    hashie (3.6.0)
     htmlcompressor (0.2.0)
     http_parser.rb (0.6.0)
     i18n (0.7.0)
@@ -56,8 +56,8 @@ GEM
       sass (>= 3.4.0, < 4.0)
     middleman-aria_current (0.1.1)
       middleman-core (~> 4.0)
-    middleman-autoprefixer (2.9.0)
-      autoprefixer-rails (~> 8.0)
+    middleman-autoprefixer (2.10.0)
+      autoprefixer-rails (>= 9.1.4)
       middleman-core (>= 3.3.3)
     middleman-cli (4.2.1)
       thor (>= 0.17.0, < 2.0)
@@ -108,14 +108,14 @@ GEM
     padrino-support (0.13.3.4)
       activesupport (>= 3.1)
     parallel (1.12.1)
-    public_suffix (3.0.2)
+    public_suffix (3.0.3)
     rack (2.0.6)
     rack-livereload (0.3.16)
       rack
     rake (12.3.2)
-    rb-fsevent (0.10.2)
-    rb-inotify (0.9.10)
-      ffi (>= 0.5.0, < 2)
+    rb-fsevent (0.10.3)
+    rb-inotify (0.10.0)
+      ffi (~> 1.0)
     redcarpet (3.4.0)
     rouge (2.1.1)
     sass (3.4.25)
@@ -136,7 +136,7 @@ GEM
     temple (0.8.0)
     thor (0.20.0)
     thread_safe (0.3.6)
-    tilt (2.0.8)
+    tilt (2.0.9)
     tzinfo (1.2.5)
       thread_safe (~> 0.1)
     uglifier (3.2.0)