Update Dockerfile

Dockerfile

@@ -37,7 +37,7 @@ RUN . /etc/os-release \
         file cpio unzip bc rsync bison flex device-tree-compiler python3-setuptools swig python3-dev ccache \
     && cp -v /etc/bbb.io/templates/apt/sbuild.list /etc/apt/sources.list.d/beagle.list \
     && apt-get clean
-RUN if [ "$ARCHNAME" == "amd64" ]; then \
+RUN if [ "$ARCHNAME" = "amd64" ]; then \
         wget "$BALENA_CLI_URL" -O balena-cli.zip \
         mkdir -p /opt ; \
         unzip balena-cli.zip -d /opt ; \