Remove version constraint on postgres driver

Gemfile

@@ -13,7 +13,7 @@ gem "psych", :platforms => :ruby_20
 gem "json"
 
 # Use postgres as the database
-gem "pg", "~> 0.18"
+gem "pg"
 
 # Use SCSS for stylesheets
 gem "sassc-rails"

Gemfile.lock

@@ -53,8 +53,8 @@ GEM
       tzinfo (~> 1.1)
     addressable (2.6.0)
       public_suffix (>= 2.0.2, < 4.0)
-    annotate (2.7.4)
-      activerecord (>= 3.2, < 6.0)
+    annotate (2.7.5)
+      activerecord (>= 3.2, < 7.0)
       rake (>= 10.4, < 13.0)
     arel (9.0.0)
     ast (2.4.0)
@@ -75,7 +75,7 @@ GEM
     bigdecimal (1.1.0)
     binding_of_caller (0.8.0)
       debug_inspector (>= 0.0.1)
-    bootsnap (1.4.3)
+    bootsnap (1.4.4)
       msgpack (~> 1.0)
     browser (2.5.3)
     builder (3.2.3)
@@ -302,7 +302,7 @@ GEM
     parallel (1.17.0)
     parser (2.6.2.1)
       ast (~> 2.4.0)
-    pg (0.21.0)
+    pg (1.1.4)
     poltergeist (1.18.1)
       capybara (>= 2.1, < 4)
       cliver (~> 0.3.1)
@@ -492,7 +492,7 @@ DEPENDENCIES
   omniauth-windowslive
   openstreetmap-deadlock_retry (>= 1.3.0)
   paperclip (~> 5.2)
-  pg (~> 0.18)
+  pg
   poltergeist
   psych
   puma (~> 3.7)
@@ -518,4 +518,4 @@ DEPENDENCIES
   webmock
 
 BUNDLED WITH
-   1.16.2
+   1.17.2