Bump middleman from 4.3.4 to 4.3.5 (#310)

Bumps [middleman](https://github.com/middleman/middleman) from 4.3.4 to 4.3.5.
- [Release notes](https://github.com/middleman/middleman/releases)
- [Changelog](https://github.com/middleman/middleman/blob/master/CHANGELOG.md)
- [Commits](https://github.com/middleman/middleman/compare/v4.3.4...v4.3.5)

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

Gemfile

@@ -1,7 +1,7 @@
 source "https://rubygems.org"
 
 gem "addressable"
-gem "middleman", "~> 4.3.4"
+gem "middleman", "~> 4.3.5"
 gem "middleman-autoprefixer"
 gem "middleman-blog"
 gem "middleman-livereload"

Gemfile.lock

@@ -18,7 +18,7 @@ GEM
     coffee-script-source (1.12.2)
     concurrent-ruby (1.1.5)
     contracts (0.13.0)
-    dotenv (2.7.4)
+    dotenv (2.7.5)
     em-websocket (0.5.1)
       eventmachine (>= 0.12.9)
       http_parser.rb (~> 0.6.0)
@@ -28,7 +28,7 @@ GEM
     fast_blank (1.0.0)
     fastimage (2.1.5)
     ffi (1.11.1)
-    haml (5.0.4)
+    haml (5.1.2)
       temple (>= 0.8.0)
       tilt
     hamster (3.0.0)
@@ -44,12 +44,12 @@ GEM
       rb-inotify (~> 0.9, >= 0.9.7)
     memoist (0.16.0)
     method_source (0.9.2)
-    middleman (4.3.4)
+    middleman (4.3.5)
       coffee-script (~> 2.2)
       haml (>= 4.0.5)
       kramdown (~> 1.2)
-      middleman-cli (= 4.3.4)
-      middleman-core (= 4.3.4)
+      middleman-cli (= 4.3.5)
+      middleman-core (= 4.3.5)
     middleman-autoprefixer (2.10.1)
       autoprefixer-rails (~> 9.1)
       middleman-core (>= 3.3.3)
@@ -57,9 +57,9 @@ GEM
       addressable (~> 2.3)
       middleman-core (>= 4.0.0)
       tzinfo (>= 0.3.0)
-    middleman-cli (4.3.4)
+    middleman-cli (4.3.5)
       thor (>= 0.17.0, < 2.0)
-    middleman-core (4.3.4)
+    middleman-core (4.3.5)
       activesupport (>= 4.2, < 5.1)
       addressable (~> 2.3)
       backports (~> 3.6)
@@ -133,7 +133,7 @@ PLATFORMS
 
 DEPENDENCIES
   addressable
-  middleman (~> 4.3.4)
+  middleman (~> 4.3.5)
   middleman-autoprefixer
   middleman-blog
   middleman-gh-pages