Bump logstasher from 1.3.0 to 2.1.5 (#257)

Bumps [logstasher](https://github.com/shadabahmed/logstasher) from 1.3.0 to 2.1.5.
- [Release notes](https://github.com/shadabahmed/logstasher/releases)
- [Changelog](https://github.com/shadabahmed/logstasher/blob/master/CHANGELOG.md)
- [Commits](shadabahmed/logstasher@v1.3.0...v2.1.5)

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

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Gemfile.lock

@@ -73,7 +73,7 @@ GEM
     celluloid-supervision (0.20.6)
       timers (>= 4.1.1)
     coderay (1.1.2)
-    concurrent-ruby (1.1.8)
+    concurrent-ruby (1.1.9)
     connection_pool (2.2.2)
     crass (1.0.6)
     database_cleaner (1.7.0)
@@ -105,16 +105,14 @@ GEM
       activesupport (>= 4.2.0)
     hitimes (1.2.6)
     honeybadger (4.8.0)
-    i18n (1.8.10)
+    i18n (1.10.0)
       concurrent-ruby (~> 1.0)
     ice_cube (0.14.0)
     json (2.3.0)
     jsonapi-renderer (0.2.0)
     jwt (1.5.6)
-    logstash-event (1.2.02)
-    logstasher (1.3.0)
-      activesupport (>= 4.0)
-      logstash-event (~> 1.2.0)
+    logstasher (2.1.5)
+      activesupport (>= 5.2)
       request_store
     loofah (2.9.1)
       crass (~> 1.0.2)
@@ -125,7 +123,7 @@ GEM
     method_source (0.9.2)
     mini_mime (1.1.0)
     mini_portile2 (2.8.0)
-    minitest (5.14.4)
+    minitest (5.15.0)
     multipart-post (2.0.0)
     mustermann (1.0.3)
     newrelic_rpm (4.7.1.340)
@@ -182,7 +180,7 @@ GEM
       thor (>= 0.19.0, < 2.0)
     rake (13.0.3)
     redis (4.1.0)
-    request_store (1.4.1)
+    request_store (1.5.1)
       rack (>= 1.4)
     responders (2.4.1)
       actionpack (>= 4.2.0, < 6.0)