Upgrade to libvips v8.13.0-rc1 (#3230)

* Switch from decompress-zip to extract-zip

The former seems to hang when unzipping a ZIP64 file that uses
the general purpose bit flag 3 as file entry.

See: https://github.com/thejoshwolfe/yauzl#no-streaming-unzip-api

* Prefer to call via static member instead

Makes it clearer that a static method is being called.

* `flatten-orange.jpg`: save without chroma subsampling

To ensure no down-scaling of the Cr/Cb channels.

test/unit/alpha.js

@@ -23,6 +23,7 @@ describe('Alpha transparency', function () {
       .flatten({
         background: { r: 255, g: 102, b: 0 }
       })
+      .jpeg({ chromaSubsampling: '4:4:4' })
       .toBuffer(function (err, data, info) {
         if (err) throw err;
         assert.strictEqual(400, info.width);
@@ -35,6 +36,7 @@ describe('Alpha transparency', function () {
     sharp(fixtures.inputPngWithTransparency)
       .resize(400, 300)
       .flatten({ background: '#ff6600' })
+      .jpeg({ chromaSubsampling: '4:4:4' })
       .toBuffer(function (err, data, info) {
         if (err) throw err;
         assert.strictEqual(400, info.width);