Update to version 3.64.0

Note that updating the generated sources is more complicated at the
moment until flatpak-node-generator starts supporting Yarn version 2+.

I had to use the code in pull request flatpak/flatpak-builder-tools#252
which adds support for Yarn version 2+.

The exact commit that I used is:
flatpak/flatpak-builder-tools@eb43ec2.

A newer update of this pull request also removes the need to execute
"$FLATPAK_BUILDER_BUILDDIR/flatpak-node/yarn2-setup.sh" before running
"yarn install" so I removed that line from the build-commands.

Commands that I used to update the generated sources are:
wget https://raw.githubusercontent.com/mifi/lossless-cut/refs/tags/v3.64.0/yarn.lock
pipx run "flatpak_node_generator @ git+https://github.com/flatpak/flatpak-builder-tools.git@refs/pull/252/head#subdirectory=node" yarn yarn.lock --output generated-sources.json
rm yarn.lock