Update tools/package.json dependencies, remove imagemin-zopfli (#35406)

imagemin-zopfli brings a lot of [vulnerable
dependencies](https://github.com/go-gitea/gitea/security/dependabot) and
it is unmaintained. The removal brings a size increase to these images,
but I think ultimately this size does not matter enough. I verified this
passes `pnpm audit` now.

tools/generate-images.js

@@ -1,5 +1,4 @@
 #!/usr/bin/env node
-import imageminZopfli from 'imagemin-zopfli'; // eslint-disable-line import-x/no-unresolved
 import {loadSVGFromString, Canvas, Rect, util} from 'fabric/node'; // eslint-disable-line import-x/no-unresolved
 import {optimize} from 'svgo';
 import {readFile, writeFile} from 'node:fs/promises';
@@ -52,7 +51,6 @@ async function generate(svg, path, {size, bg}) {
     png = Buffer.concat([png, chunk]);
   }
 
-  png = await imageminZopfli({more: true})(png);
   await writeFile(outputFile, png);
 }