Bump Ruby to 3.3.4 (#836)

Ruby 3.3.4 has fixes for some regressions in 3.3.3. I don't think it
affects us but still good to upgrade.

Author: tgxworld

image/base/slim.Dockerfile

@@ -5,7 +5,7 @@ ARG DEBIAN_RELEASE=bookworm
 FROM debian:${DEBIAN_RELEASE}-slim
 
 ARG DEBIAN_RELEASE
-ARG RUBY_VERSION=3.3.3
+ARG RUBY_VERSION=3.3.4
 ENV PG_MAJOR=13 \
     RUBY_ALLOCATOR=/usr/lib/libjemalloc.so \
     RUSTUP_HOME=/usr/local/rustup \