Lock gem versions for all relevant platforms

We run DTI on a few different architectures in practice, and the `vendor/cache` directory can be a bit confusing to manage when switching dev machines.

In this change, we add all our common dev machine platforms to the Gemfile.lock, so precompiled gems for all of them are cached, granting us resilience against the possibility of Rubygems going down, and speeding up deploys & installation.

Gemfile.lock

@@ -179,6 +179,9 @@ GEM
     faraday-net_http (3.4.2)
       net-http (~> 0.5)
     ffi (1.17.2)
+    ffi (1.17.2-aarch64-linux-gnu)
+    ffi (1.17.2-arm64-darwin)
+    ffi (1.17.2-x86_64-linux-gnu)
     fiber-annotation (0.2.0)
     fiber-local (1.1.0)
       fiber-storage
@@ -263,6 +266,12 @@ GEM
     nokogiri (1.18.10)
       mini_portile2 (~> 2.8.2)
       racc (~> 1.4)
+    nokogiri (1.18.10-aarch64-linux-gnu)
+      racc (~> 1.4)
+    nokogiri (1.18.10-arm64-darwin)
+      racc (~> 1.4)
+    nokogiri (1.18.10-x86_64-linux-gnu)
+      racc (~> 1.4)
     omniauth (2.1.4)
       hashie (>= 3.4.6)
       logger
@@ -530,7 +539,10 @@ GEM
     zeitwerk (2.7.4)
 
 PLATFORMS
+  aarch64-linux
+  arm64-darwin
   ruby
+  x86_64-linux
 
 DEPENDENCIES
   RocketAMF!