UPX compression issue in current(v1.15.2) release.

[riKirsti]

I noticed that the UPX has a compression issue in the release github action logs. Probably also in the former release.

It was a known bug and had already been fixed in upx v4.02. But the main Linux distributions still only use upx 3.96, so does the github action ubuntu-latest.
I have a temporary workaround for this. Download and use the precompiled version of UPX in build-release.yml instead of apt-get install -y upx.
wget -q https://github.com/upx/upx/releases/download/v4.0.2/upx-4.0.2-amd64_linux.tar.xz -O /tmp/upx-4.0.2.tar.xz&&mkdir -p /tmp/upx&&xz -d -c /tmp/upx-4.0.2.tar.xz | tar -x -C /tmp/upx; chmod +x /tmp/upx/upx-4.0.2-amd64_linux/upx&&export PATH=/tmp/upx/upx-4.0.2-amd64_linux:$PATH;
I got compression success and they are function well on my OpenWrt router for a month. Also tested on the lasted shadowsocks-rust commit.

BTW, based on the UPX doc, I recommend use upx --lzma --best instead of upx -9 in build-release to get better compression ratio and I can confirm this will not break shadowsocks-rust's functions.

Thank you for your remarkable efforts on this great project.

[zonyitoo]

I am Ok for these changes. Please make a PR.

[riKirsti]

PR for this. #1123