Update pg to version 1.6.3 (#61)

Co-authored-by: depfu[bot] <23717796+depfu[bot]@users.noreply.github.com>

Author: depfu[bot]

Gemfile.lock

@@ -395,7 +395,7 @@ GEM
       hashery (~> 2.0)
       ruby-rc4
       ttfunk
-    pg (1.5.3)
+    pg (1.6.3)
     prawn (2.4.0)
       pdf-core (~> 0.9.0)
       ttfunk (~> 1.7)