Update docker image (#455)

For some reason despite specifying ruby 3.1 it was updated to 3.3. This
updates everything to 3.3.

Co-authored-by: Hendrik Kleinwaechter <hendricius@hendricius.fritz.box>

Dockerfile

@@ -18,7 +18,7 @@ RUN apt-get update && \
     zip \
     git \
     wget \
-    ruby3.1 \
+    ruby3.3 \
     ruby-dev \
     imagemagick \
     rsync \

website/.ruby-version

@@ -1 +1 @@
-3.1.2
+3.3.7

website/Gemfile.lock

@@ -3,11 +3,9 @@ GEM
   specs:
     coderay (1.1.3)
     method_source (1.0.0)
-    nokogiri (1.15.3-arm64-darwin)
-      racc (~> 1.4)
-    nokogiri (1.15.3-x86_64-darwin)
-      racc (~> 1.4)
-    nokogiri (1.15.3-x86_64-linux)
+    mini_portile2 (2.8.8)
+    nokogiri (1.15.3)
+      mini_portile2 (~> 2.8.2)
       racc (~> 1.4)
     pry (0.14.2)
       coderay (~> 1.1)
@@ -16,6 +14,7 @@ GEM
 
 PLATFORMS
   arm64-darwin-22
+  arm64-darwin-24
   x86_64-darwin-22
   x86_64-linux
 
@@ -24,7 +23,7 @@ DEPENDENCIES
   pry
 
 RUBY VERSION
-   ruby 3.1.2p20
+   ruby 3.3.7p123
 
 BUNDLED WITH
    2.4.12