Fix newline written to private key

Author: huntfx

.github/workflows/build-executable.yml

@@ -251,7 +251,7 @@ jobs:
         shell: bash
         run: |
           source .venv/Scripts/activate
-          echo "$PRIVATE_SIGNING_KEY" > keys/private.key
+          echo -n "$PRIVATE_SIGNING_KEY" > keys/private.key
           python launch.py --sign-executable "dist/MouseTracks.exe"
           python launch.py --sign-executable "dist/${FULL_EXE_NAME}"
           rm keys/private.key