Use sed instead of patch for char limit

Dockerfile

@@ -93,9 +93,8 @@ RUN ldconfig && \
 # Download Mastodon source
 RUN curl -L https://github.com/tootsuite/mastodon/archive/v${MASTODON_VERSION}.tar.gz | tar -xz --strip-components 1 -f -
 
-# Apply character limit patch
-COPY char-limit.patch /tmp/
-RUN patch -p1 < /tmp/char-limit.patch
+RUN sed -i 's/MAX_CHARS = 500/MAX_CHARS = 2500/g' app/validators/status_length_validator.rb && \
+    sed -i "s/max_characters'], 500)/max_characters'], 2500)/g" app/javascript/mastodon/features/compose/containers/compose_form_container.js
 
 # Install Ruby dependencies
 RUN bundle config --local set deployment 'true' && \