fix: add missing TARGETARCH definition

Author: lsorber

Dockerfile

@@ -9,6 +9,7 @@ RUN apt-get update && \
     rm -rf /var/lib/apt/lists/*
 
 # Install Miniconda.
+ARG TARGETARCH
 RUN CONDA_ARCH=$([ "$TARGETARCH" = "arm64" ] && echo "aarch64" || echo "x86_64") && \
     wget --quiet "https://repo.anaconda.com/miniconda/Miniconda3-latest-Linux-$CONDA_ARCH.sh" --output-document ~/miniconda.sh && \
     /bin/bash ~/miniconda.sh -b -p /opt/conda && \