Merge pull request #2731 from DFE-Digital/dependabot/bundler/combine_pdf-1.0.31

Bump combine_pdf from 1.0.29 to 1.0.31

Author: syed87

Gemfile.lock

@@ -154,7 +154,7 @@ GEM
     choice (0.2.0)
     climate_control (1.2.0)
     coderay (1.1.3)
-    combine_pdf (1.0.29)
+    combine_pdf (1.0.31)
       matrix
       ruby-rc4 (>= 0.1.5)
     concurrent-ruby (1.3.5)