gems: add back pry gem.

The `pry` gem was removed in e698bf91 because we replaced `pry-byebug` with the standard debugger.
Add it back because `pry` is better than `irb` and we still can use the standard debugger with it.

Gemfile

@@ -59,6 +59,7 @@ gem "composite_primary_keys"
 gem "resolv"
 gem "rover-df"
 gem "ffi-libarchive"
+gem "pry-rails"
 
 group :development do
   gem 'rubocop', require: false

Gemfile.lock

@@ -332,6 +332,11 @@ GEM
       ast (~> 2.4.1)
     pg (1.3.5)
     prometheus-client (4.0.0)
+    pry (0.14.1)
+      coderay (~> 1.1)
+      method_source (~> 1.0)
+    pry-rails (0.3.9)
+      pry (>= 0.10.4)
     public_suffix (5.0.0)
     puma (6.0.0)
       nio4r (~> 2.0)
@@ -573,6 +578,7 @@ DEPENDENCIES
   oauth2
   parallel
   pg
+  pry-rails
   public_suffix
   puma
   puma-metrics