Bump webmock from 3.20.0 to 3.21.0 (#2226)

Author: dependabot[bot]

Gemfile.lock

@@ -153,7 +153,7 @@ GEM
     coderay (1.1.3)
     concurrent-ruby (1.2.3)
     connection_pool (2.4.1)
-    crack (0.4.6)
+    crack (1.0.0)
       bigdecimal
       rexml
     crass (1.0.6)
@@ -521,7 +521,7 @@ GEM
       activemodel (>= 6.0.0)
       bindex (>= 0.4.0)
       railties (>= 6.0.0)
-    webmock (3.20.0)
+    webmock (3.21.0)
       addressable (>= 2.8.0)
       crack (>= 0.3.2)
       hashdiff (>= 0.4.0, < 2.0.0)