Add Gemfile.lock to git

See https://stackoverflow.com/questions/4151495/should-gemfile-lock-be-included-in-gitignore

.gitignore

@@ -2,9 +2,6 @@ _site/
 .sass-cache/
 .jekyll-metadata
 .tweet-cache
-alembic-jekyll-theme-*.gem
-Gemfile.lock
-**/Gemfile.lock
 .bundle
 /vendor
 .DS_Store

Gemfile.lock

+GEM
+  remote: https://rubygems.org/
+  specs:
+    activesupport (3.2.22.5)
+      i18n (~> 0.6, >= 0.6.4)
+      multi_json (~> 1.0)
+    addressable (2.7.0)
+      public_suffix (>= 2.0.2, < 5.0)
+    alembic-jekyll-theme (2.3.1)
+      jekyll (~> 3.6)
+      jekyll-default-layout (~> 0.1)
+      jekyll-feed (~> 0.9)
+      jekyll-mentions (~> 1.2)
+      jekyll-paginate (~> 1.1)
+      jekyll-redirect-from (~> 0.12)
+      jekyll-seo-tag (~> 2.3)
+      jekyll-sitemap (~> 0.13)
+      jemoji (~> 0.9)
+    colorator (1.1.0)
+    concurrent-ruby (1.1.8)
+    em-websocket (0.5.2)
+      eventmachine (>= 0.12.9)
+      http_parser.rb (~> 0.6.0)
+    eventmachine (1.2.7)
+    ffi (1.14.2)
+    forwardable-extended (2.6.0)
+    gemoji (3.0.1)
+    html-pipeline (2.14.0)
+      activesupport (>= 2)
+      nokogiri (>= 1.4)
+    http_parser.rb (0.6.0)
+    i18n (0.9.5)
+      concurrent-ruby (~> 1.0)
+    jekyll (3.9.0)
+      addressable (~> 2.4)
+      colorator (~> 1.0)
+      em-websocket (~> 0.5)
+      i18n (~> 0.7)
+      jekyll-sass-converter (~> 1.0)
+      jekyll-watch (~> 2.0)
+      kramdown (>= 1.17, < 3)
+      liquid (~> 4.0)
+      mercenary (~> 0.3.3)
+      pathutil (~> 0.9)
+      rouge (>= 1.7, < 4)
+      safe_yaml (~> 1.0)
+    jekyll-default-layout (0.1.5)
+      jekyll (>= 3.0, < 5.0)
+    jekyll-feed (0.15.1)
+      jekyll (>= 3.7, < 5.0)
+    jekyll-mentions (1.6.0)
+      html-pipeline (~> 2.3)
+      jekyll (>= 3.7, < 5.0)
+    jekyll-paginate (1.1.0)
+    jekyll-redirect-from (0.16.0)
+      jekyll (>= 3.3, < 5.0)
+    jekyll-sass-converter (1.5.2)
+      sass (~> 3.4)
+    jekyll-seo-tag (2.7.1)
+      jekyll (>= 3.8, < 5.0)
+    jekyll-sitemap (0.13.0)
+      jekyll (~> 3.3)
+    jekyll-twitter-plugin (2.1.0)
+    jekyll-watch (2.2.1)
+      listen (~> 3.0)
+    jemoji (0.12.0)
+      gemoji (~> 3.0)
+      html-pipeline (~> 2.2)
+      jekyll (>= 3.0, < 5.0)
+    kramdown (2.3.0)
+      rexml
+    kramdown-parser-gfm (1.1.0)
+      kramdown (~> 2.0)
+    liquid (4.0.3)
+    listen (3.4.1)
+      rb-fsevent (~> 0.10, >= 0.10.3)
+      rb-inotify (~> 0.9, >= 0.9.10)
+    mercenary (0.3.6)
+    mini_portile2 (2.5.0)
+    multi_json (1.15.0)
+    nokogiri (1.11.1)
+      mini_portile2 (~> 2.5.0)
+      racc (~> 1.4)
+    pathutil (0.16.2)
+      forwardable-extended (~> 2.6)
+    public_suffix (4.0.6)
+    racc (1.5.2)
+    rb-fsevent (0.10.4)
+    rb-inotify (0.10.1)
+      ffi (~> 1.0)
+    rexml (3.2.4)
+    rouge (3.26.0)
+    safe_yaml (1.0.5)
+    sass (3.7.4)
+      sass-listen (~> 4.0.0)
+    sass-listen (4.0.0)
+      rb-fsevent (~> 0.9, >= 0.9.4)
+      rb-inotify (~> 0.9, >= 0.9.7)
+    tzinfo (2.0.4)
+      concurrent-ruby (~> 1.0)
+    tzinfo-data (1.2021.1)
+      tzinfo (>= 1.0.0)
+
+PLATFORMS
+  ruby
+
+DEPENDENCIES
+  alembic-jekyll-theme (~> 2.2)
+  jekyll (~> 3.4)
+  jekyll-default-layout
+  jekyll-feed
+  jekyll-paginate
+  jekyll-redirect-from
+  jekyll-seo-tag
+  jekyll-sitemap
+  jekyll-twitter-plugin
+  jemoji
+  kramdown-parser-gfm
+  tzinfo
+  tzinfo-data
+
+BUNDLED WITH
+   1.17.3