Update minimum Ruby version and gems (#424)

* Update minimum Ruby version to at least the version run by ASF infra
  team on Jekyll builders, so that way we can reduce compatibility
  surprises when trying to build on stuff substantially newer than
  what's on ASF's infrastructure
* Do a bundle update

Gemfile

@@ -1,4 +1,4 @@
-ruby '>=2.5.1'
+ruby '>=2.7'
 source 'https://rubygems.org'
 gem 'jekyll', '>= 4.2.0'
 gem 'jekyll-redirect-from', '>= 0.16.0'

Gemfile.lock

@@ -1,21 +1,22 @@
 GEM
   remote: https://rubygems.org/
   specs:
-    addressable (2.8.4)
+    addressable (2.8.6)
       public_suffix (>= 2.0.2, < 6.0)
     colorator (1.1.0)
-    concurrent-ruby (1.2.2)
+    concurrent-ruby (1.2.3)
     em-websocket (0.5.3)
       eventmachine (>= 0.12.9)
       http_parser.rb (~> 0)
     eventmachine (1.2.7)
-    ffi (1.15.5)
+    ffi (1.16.3)
     forwardable-extended (2.6.0)
-    google-protobuf (3.23.4-x86_64-linux)
+    google-protobuf (4.26.1-x86_64-linux)
+      rake (>= 13)
     http_parser.rb (0.8.0)
-    i18n (1.14.1)
+    i18n (1.14.4)
       concurrent-ruby (~> 1.0)
-    jekyll (4.3.2)
+    jekyll (4.3.3)
       addressable (~> 2.4)
       colorator (~> 1.0)
       em-websocket (~> 0.5)
@@ -42,24 +43,25 @@ GEM
     kramdown-parser-gfm (1.1.0)
       kramdown (~> 2.0)
     liquid (4.0.4)
-    listen (3.8.0)
+    listen (3.9.0)
       rb-fsevent (~> 0.10, >= 0.10.3)
       rb-inotify (~> 0.9, >= 0.9.10)
     mercenary (0.4.0)
     pathutil (0.16.2)
       forwardable-extended (~> 2.6)
-    public_suffix (5.0.3)
+    public_suffix (5.0.5)
+    rake (13.2.1)
     rb-fsevent (0.11.2)
     rb-inotify (0.10.1)
       ffi (~> 1.0)
     rexml (3.2.6)
-    rouge (4.1.2)
+    rouge (4.2.1)
     safe_yaml (1.0.5)
-    sass-embedded (1.64.1-x86_64-linux-gnu)
-      google-protobuf (~> 3.23)
+    sass-embedded (1.76.0-x86_64-linux-gnu)
+      google-protobuf (>= 3.25, < 5.0)
     terminal-table (3.0.2)
       unicode-display_width (>= 1.1.1, < 3)
-    unicode-display_width (2.4.2)
+    unicode-display_width (2.5.0)
     webrick (1.8.1)
 
 PLATFORMS