Update dependency spring to v4.3.0

Author: renovate[bot]

api/Gemfile.lock

@@ -304,7 +304,7 @@ GEM
     simplecov-html (0.12.3)
     simplecov_json_formatter (0.1.4)
     slack-notifier (2.4.0)
-    spring (4.1.1)
+    spring (4.3.0)
     spring-commands-rspec (1.0.4)
       spring (>= 0.9.1)
     sprockets (3.7.2)