[Ruby] Update to 3.1

net-smtp is no longer bundled by default
Webrick is no longer bundled by default, new rails projects are created
with puma in the gemfile

.ruby-version

@@ -1 +1 @@
-2.7.3
+3.1.2

Dockerfile

@@ -1,4 +1,4 @@
-FROM ruby:2.7.3-alpine
+FROM ruby:3.1.2-alpine
 
 # Dependencies for setup and runtime
 RUN apk --no-cache add nodejs yarn postgresql-client ffmpeg vips tzdata \

Gemfile

@@ -38,6 +38,7 @@ gem 'elasticsearch-rails'
 
 gem 'mailgun-ruby'
 gem 'resolv'
+gem 'net-smtp'
 
 # needed for looser jpeg header compat
 gem 'ruby-imagespec', :require => "image_spec", :git => "https://github.com/r888888888/ruby-imagespec.git", :branch => "exif-fixes"
@@ -55,6 +56,7 @@ group :development, :test do
   gem 'awesome_print'
   gem 'pry-byebug'
   gem 'listen'
+  gem 'puma'
 end
 
 group :test do

Gemfile.lock

@@ -107,6 +107,7 @@ GEM
     crass (1.0.6)
     dalli (3.1.5)
     diff-lcs (1.5.0)
+    digest (3.1.0)
     docile (1.4.0)
     domain_name (0.5.20190701)
       unf (>= 0.0.5, < 1.0.0)
@@ -208,6 +209,12 @@ GEM
     multi_json (1.15.0)
     multi_xml (0.6.0)
     multipart-post (2.1.1)
+    net-protocol (0.1.3)
+      timeout
+    net-smtp (0.3.1)
+      digest
+      net-protocol
+      timeout
     netrc (0.11.0)
     newrelic_rpm (8.2.0)
     nio4r (2.5.8)
@@ -225,6 +232,8 @@ GEM
       byebug (~> 11.0)
       pry (~> 0.13.0)
     public_suffix (4.0.6)
+    puma (5.6.4)
+      nio4r (~> 2.0)
     racc (1.6.0)
     rack (2.2.3)
     rack-proxy (0.7.0)
@@ -323,6 +332,7 @@ GEM
       multi_json (~> 1.8)
     thor (1.2.1)
     timecop (0.9.4)
+    timeout (0.2.0)
     tzinfo (2.0.4)
       concurrent-ruby (~> 1.0)
     unf (0.1.4)
@@ -380,9 +390,11 @@ DEPENDENCIES
   minitest-ci
   mocha
   mock_redis
+  net-smtp
   newrelic_rpm
   pg
   pry-byebug
+  puma
   rails (~> 6.1)
   recaptcha
   redis