add aarch64-unknown-linux-gnu to release workflow (#79)

Author: mfreeborn

.github/workflows/build_releases.yml

@@ -15,7 +15,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        target: [x86_64-unknown-linux-gnu, armv7-unknown-linux-gnueabihf, arm-unknown-linux-gnueabihf]
+        target: [x86_64-unknown-linux-gnu, armv7-unknown-linux-gnueabihf, arm-unknown-linux-gnueabihf, aarch64-unknown-linux-gnu]
 
     steps:
       - uses: actions/checkout@v3