Upgrade bundler to the 2.x line

PragTob · PragTob · commit a27e07f98e6e · 2020-01-27T12:21:10.000+01:00
1.17.3 is older than a year, bundler 2 is safe to use after
it's initial issues :)
diff --git a/Gemfile.lock b/Gemfile.lock
@@ -274,4 +274,4 @@ DEPENDENCIES
   webpacker (~> 3.5)
 
 BUNDLED WITH
-   1.17.3
+   2.1.4
