Check that pixi is executable (#1)

Dockerfile

@@ -8,7 +8,8 @@ RUN apt update && apt install -y curl
 # download the musl build since the gnu build is not available on aarch64
 RUN curl -Ls \
     "https://github.com/prefix-dev/pixi/releases/download/v${PIXI_VERSION}/pixi-$(uname -m)-unknown-linux-musl" \
-    -o /pixi
+    -o /pixi && chmod +x /pixi
+RUN /pixi --version
 
 FROM --platform=$TARGETPLATFORM $BASE_IMAGE
 COPY --from=builder --chown=root:root --chmod=0555 /pixi /usr/local/bin/pixi