Bump middleman from 4.3.3 to 4.3.4 (olivierlacan#302)

Bumps [middleman](https://github.com/middleman/middleman) from 4.3.3 to 4.3.4.
- [Release notes](https://github.com/middleman/middleman/releases)
- [Changelog](https://github.com/middleman/middleman/blob/master/CHANGELOG.md)
- [Commits](middleman/middleman@v4.3.3...v4.3.4)

Signed-off-by: dependabot[bot] <[email protected]>

Gemfile

@@ -1,7 +1,7 @@
 source "https://rubygems.org"
 
 gem "addressable"
-gem "middleman", "~> 4.3.3"
+gem "middleman", "~> 4.3.4"
 gem "middleman-autoprefixer"
 gem "middleman-blog"
 gem "middleman-livereload"

Gemfile.lock

@@ -1,7 +1,7 @@
 GEM
   remote: https://rubygems.org/
   specs:
-    activesupport (5.0.7.1)
+    activesupport (5.0.7.2)
       concurrent-ruby (~> 1.0, >= 1.0.2)
       i18n (>= 0.7, < 2)
       minitest (~> 5.1)
@@ -10,15 +10,15 @@ GEM
       public_suffix (>= 2.0.2, < 4.0)
     autoprefixer-rails (9.4.10.2)
       execjs
-    backports (3.12.0)
+    backports (3.14.0)
     coderay (1.1.2)
     coffee-script (2.4.1)
       coffee-script-source
       execjs
     coffee-script-source (1.12.2)
-    concurrent-ruby (1.1.4)
+    concurrent-ruby (1.1.5)
     contracts (0.13.0)
-    dotenv (2.7.1)
+    dotenv (2.7.2)
     em-websocket (0.5.1)
       eventmachine (>= 0.12.9)
       http_parser.rb (~> 0.6.0)
@@ -44,22 +44,22 @@ GEM
       rb-inotify (~> 0.9, >= 0.9.7)
     memoist (0.16.0)
     method_source (0.9.2)
-    middleman (4.3.3)
+    middleman (4.3.4)
       coffee-script (~> 2.2)
       haml (>= 4.0.5)
       kramdown (~> 1.2)
-      middleman-cli (= 4.3.3)
-      middleman-core (= 4.3.3)
+      middleman-cli (= 4.3.4)
+      middleman-core (= 4.3.4)
     middleman-autoprefixer (2.10.1)
       autoprefixer-rails (~> 9.1)
       middleman-core (>= 3.3.3)
     middleman-blog (4.0.3)
       addressable (~> 2.3)
       middleman-core (>= 4.0.0)
       tzinfo (>= 0.3.0)
-    middleman-cli (4.3.3)
+    middleman-cli (4.3.4)
       thor (>= 0.17.0, < 2.0)
-    middleman-core (4.3.3)
+    middleman-core (4.3.4)
       activesupport (>= 4.2, < 5.1)
       addressable (~> 2.3)
       backports (~> 3.6)
@@ -101,12 +101,12 @@ GEM
       tilt (>= 1.4.1, < 3)
     padrino-support (0.13.3.4)
       activesupport (>= 3.1)
-    parallel (1.14.0)
+    parallel (1.17.0)
     pry (0.12.2)
       coderay (~> 1.1.0)
       method_source (~> 0.9.0)
     public_suffix (3.0.3)
-    rack (2.0.6)
+    rack (2.0.7)
     rack-livereload (0.3.16)
       rack
     rake (12.3.2)
@@ -119,7 +119,7 @@ GEM
       ffi (~> 1.9)
       rake
     servolux (0.13.0)
-    temple (0.8.0)
+    temple (0.8.1)
     thor (0.20.3)
     thread_safe (0.3.6)
     tilt (2.0.9)
@@ -133,7 +133,7 @@ PLATFORMS
 
 DEPENDENCIES
   addressable
-  middleman (~> 4.3.3)
+  middleman (~> 4.3.4)
   middleman-autoprefixer
   middleman-blog
   middleman-gh-pages