Put every Ruby pin on 3.4.10

Three pins, two values: Dockerfile said 3.4.5, Dockerfile-export said
3.4.7, .ruby-version said 3.4.5 — the export image had already been
bumped on its own and nobody noticed the other two lagging. Both
Dockerfiles carry a comment telling you to keep them in step.

3.4.10 is the current 3.4.x. CI resolves its Ruby from .ruby-version,
so this is the version the tests now run under.

.ruby-version

@@ -1 +1 @@
-3.4.5
+3.4.10

Dockerfile

@@ -1,7 +1,7 @@
 # syntax = docker/dockerfile:1
 
 # Make sure it matches the Ruby version in .ruby-version and Gemfile
-ARG RUBY_VERSION=3.4.5
+ARG RUBY_VERSION=3.4.10
 FROM docker.io/library/ruby:$RUBY_VERSION-slim AS base
 
 # Rails app lives here

Dockerfile-export

@@ -1,7 +1,7 @@
 # syntax = docker/dockerfile:1
 
 # Make sure it matches the Ruby version in .ruby-version and Gemfile
-ARG RUBY_VERSION=3.4.7
+ARG RUBY_VERSION=3.4.10
 FROM ruby:$RUBY_VERSION-slim as base
 
 # Install the tools we need