fix: Gemfile & Gemfile.lock to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-RUBY-PUMA-8062124

Gemfile

@@ -10,7 +10,7 @@ gem 'rails', '~> 6.1', '>= 6.1.7.8'
 # Use postgres as the database for Active Record
 gem 'pg', '>= 0.4.4'
 # Use Puma as the app server
-gem 'puma', '>= 6.4.2'
+gem 'puma', '>= 6.4.3'
 # Use SCSS for stylesheets
 gem 'sass-rails', '>= 6.0.0'
 # Use Uglifier as compressor for JavaScript assets

Gemfile.lock

@@ -173,7 +173,7 @@ GEM
     faraday_middleware (1.2.0)
       faraday (~> 1.0)
     ffi (1.17.0)
-    ffi (1.17.0-x86_64-linux-gnu)
+    ffi (1.17.0-x86_64-linux)
     ffi-compiler (1.3.2)
       ffi (>= 1.15.5)
       rake
@@ -273,7 +273,7 @@ GEM
     psych (5.1.2)
       stringio
     public_suffix (6.0.0)
-    puma (6.4.2)
+    puma (6.4.3)
       nio4r (~> 2.0)
     racc (1.8.0)
     rack (2.2.9)
@@ -469,7 +469,7 @@ DEPENDENCIES
   oauthenticator (~> 1.4, >= 1.4.1)
   pg (>= 0.4.4)
   popper_js (>= 1.16)
-  puma (>= 6.4.2)
+  puma (>= 6.4.3)
   rails (~> 6.1, >= 6.1.7.8)
   rails_lti2_provider!
   rdoc
@@ -490,3 +490,6 @@ DEPENDENCIES
   tzinfo-data
   web-console (>= 4.2.1)
   webmock (>= 3.23.1)
+
+BUNDLED WITH
+   2.1.4