build: add linux arm64 binary to release builds

Adds aarch64-unknown-linux-gnu target using GitHub's native ARM64
runner. Closes #13.

Author: realfresh

.github/workflows/release.yml

@@ -62,6 +62,9 @@ jobs:
           - name: linux-amd64
             runner: ubuntu-latest
             target: x86_64-unknown-linux-gnu
+          - name: linux-arm64
+            runner: ubuntu-24.04-arm
+            target: aarch64-unknown-linux-gnu
           # == Windows == #
           - name: win-amd64
             runner: windows-latest