Bump sorcery from 0.14.0 to 0.15.0

Bumps [sorcery](https://github.com/Sorcery/sorcery) from 0.14.0 to 0.15.0.
- [Release notes](https://github.com/Sorcery/sorcery/releases)
- [Changelog](https://github.com/Sorcery/sorcery/blob/master/CHANGELOG.md)
- [Commits](Sorcery/sorcery@v0.14.0...v0.15.0)

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

Gemfile.lock

@@ -77,7 +77,7 @@ GEM
     crass (1.0.6)
     erubi (1.9.0)
     execjs (2.7.0)
-    faraday (1.0.0)
+    faraday (1.0.1)
       multipart-post (>= 1.2, < 3)
     ffi (1.12.2)
     globalid (0.4.2)
@@ -115,7 +115,7 @@ GEM
     nokogiri (1.10.8)
       mini_portile2 (~> 2.4.0)
     oauth (0.5.4)
-    oauth2 (1.4.3)
+    oauth2 (1.4.4)
       faraday (>= 0.8, < 2.0)
       jwt (>= 1.0, < 3.0)
       multi_json (~> 1.3)
@@ -129,7 +129,7 @@ GEM
       terrapin (~> 0.6.0)
     public_suffix (4.0.3)
     puma (3.12.4)
-    rack (2.1.2)
+    rack (2.2.2)
     rack-test (1.1.0)
       rack (>= 1.0, < 3)
     rails (5.2.4.1)
@@ -177,7 +177,7 @@ GEM
     selenium-webdriver (3.142.7)
       childprocess (>= 0.5, < 4.0)
       rubyzip (>= 1.2.2)
-    sorcery (0.14.0)
+    sorcery (0.15.0)
       bcrypt (~> 3.1)
       oauth (~> 0.4, >= 0.4.4)
       oauth2 (~> 1.0, >= 0.8.0)