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
diff --git a/Gemfile b/Gemfile
index 3b83265..9387815 100644
--- a/Gemfile
+++ b/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'
diff --git a/Gemfile.lock b/Gemfile.lock
index 4e345db..e2227c0 100644
--- a/Gemfile.lock
+++ b/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 @@
     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)
 
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