Add .ruby-version, delete srht build config

.build.yml

@@ -1,19 +0,0 @@
-image: alpine/edge
-packages:
-    - ruby
-    - ruby-dev
-    - ruby-bundler
-    - hut
-oauth: pages.sr.ht/PAGES:RW
-environment:
-    site: farthergate.com
-tasks:
-    - build: |
-          cd farthergate.com
-          bundle install --path vendor/bundle
-          bundle exec ruby build.rb
-    - package: |
-          cd farthergate.com/_build
-          tar -cvz . > ../../site.tar.gz
-    - upload: |
-          hut pages publish -d $site site.tar.gz

.ruby-version

@@ -0,0 +1 @@
+3.3.6