chore(ci): Remove use of undefined variable

.github/workflows/post-release.yml

@@ -94,7 +94,7 @@ jobs:
     - name: Build archive
       shell: bash
       run: |
-        outdir="./target/${{ env.TARGET_DIR }}/release"
+        outdir="./target/${{ matrix.target }}/release"
         staging="${{ env.BIN_NAME }}-${{ needs.create-release.outputs.release_version }}-${{ matrix.target }}"
         mkdir -p "$staging"/{complete,doc}
         cp {README.md,LICENSE-*} "$staging/"