Added wdm gem for Windows systems

Gemfile

@@ -13,4 +13,5 @@ gem 'pandoc-ruby', '~> 2.1'
 
 # Use rerun gem to auto-reload app
 gem 'rerun'
+gem 'wdm', '>= 0.1.0' if Gem.win_platform?
 

Gemfile.lock

@@ -2,6 +2,7 @@ GEM
   remote: https://rubygems.org/
   specs:
     ffi (1.15.5)
+    ffi (1.15.5-x64-mingw-ucrt)
     kramdown (2.4.0)
       rexml
     listen (3.8.0)
@@ -36,10 +37,13 @@ GEM
       rack-protection (= 3.0.5)
       sinatra (= 3.0.5)
       tilt (~> 2.0)
+    sqlite3 (1.6.1-x64-mingw-ucrt)
     sqlite3 (1.6.1-x86_64-linux)
     tilt (2.1.0)
+    wdm (0.1.1)
 
 PLATFORMS
+  x64-mingw-ucrt
   x86_64-linux
 
 DEPENDENCIES
@@ -51,6 +55,7 @@ DEPENDENCIES
   sinatra (~> 3.0)
   sinatra-contrib (~> 3.0)
   sqlite3 (~> 1.6)
+  wdm (>= 0.1.0)
 
 BUNDLED WITH
    2.3.5