Bump nokogiri from 1.6.6.2 to 1.13.4

Bumps [nokogiri](https://github.com/sparklemotion/nokogiri) from 1.6.6.2 to 1.13.4.
- [Release notes](https://github.com/sparklemotion/nokogiri/releases)
- [Changelog](https://github.com/sparklemotion/nokogiri/blob/v1.13.4/CHANGELOG.md)
- [Commits](sparklemotion/nokogiri@v1.6.6.2...v1.13.4)

---
updated-dependencies:
- dependency-name: nokogiri
  dependency-type: indirect
...

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

Author: dependabot[bot]

Diff for: Gemfile.lock

@@ -3,20 +3,22 @@ PATH
   specs:
     postgres_to_redshift (0.1.2)
       aws-sdk-v1 (~> 1.54)
-      pg (~> 0.17.0)
+      pg (~> 0.18.0)
 
 GEM
   remote: https://rubygems.org/
   specs:
-    aws-sdk-v1 (1.66.0)
+    aws-sdk-v1 (1.67.0)
       json (~> 1.4)
-      nokogiri (>= 1.4.4)
+      nokogiri (~> 1)
     diff-lcs (1.2.5)
-    json (1.8.3)
-    mini_portile (0.6.2)
-    nokogiri (1.6.6.2)
-      mini_portile (~> 0.6.0)
-    pg (0.17.1)
+    json (1.8.6)
+    mini_portile2 (2.8.0)
+    nokogiri (1.13.4)
+      mini_portile2 (~> 2.8.0)
+      racc (~> 1.4)
+    pg (0.18.4)
+    racc (1.6.0)
     rake (10.4.2)
     rspec (3.2.0)
       rspec-core (~> 3.2.0)