ci: build fully-static Linux binary with musl to fix glibc version errors

[MiaM1ku]

Problem

The current nightly release (pumpkin-X64-Linux) is linked against glibc 2.39, so it fails on older distributions with:

GLIBC_2.39 not found

Solution

Add a new job build_release_static that compiles for x86_64-unknown-linux-musl and uploads the fully-static binary.
The new artifact is named pumpkin-x86_64-linux-musl and is shipped together with the existing GNU build in the nightly release.

Changes

• Install musl-tools (provides x86_64-linux-musl-gcc)
• Add rustup target add x86_64-unknown-linux-musl
• Build with cargo build --release --target x86_64-unknown-linux-musl
• Include the static binary in draft_release

Verification

• CI passes
• Artifacts contain pumpkin-x86_64-linux-musl
• Downloaded binary shows statically linked via file pumpkin-x86_64-linux-musl

[illyrius666]

the comments, remove them or make them english.

[HttpRafa]

We could also use cargo-zigbuild to build Pumpkin for an older glibc version. This might avoid some of the negative effects of using musl, such as increased binary size.

[Snowiiii]

Hey, I'm sorry but i don' think this is necessary and the "userbase" for this is very small, glibc 2.39 released a year ago, enough time for the most distros to update their glibc package, Also if using an older distro the user still always has the option to install glibc manually

[MiaM1ku]

Hey, I'm sorry but i don' think this is necessary and the "userbase" for this is very small, glibc 2.39 released a year ago, enough time for the most distros to update their glibc package, Also if using an older distro the user still always has the option to install glibc manually

For some users, there are various reasons why they may still be on older systems. Upgrading glibc is not as straightforward as it might seem and can easily introduce system instability or breakages. Keeping a statically linked build provides a safer alternative and helps these users avoid the risks associated with manually upgrading glibc.