Update Dockerfile

Author: RainPPR

Dockerfile

@@ -48,7 +48,7 @@ COPY scripts/ /app/scripts/
 COPY --chmod=755 bin/ /usr/local/bin/
 
 RUN git clone --depth 1 https://github.com/raineblog/mkdocs-material.git && \
-    python3 scripts/install_katex.py && \
+    python scripts/install_katex.py && \
     pip install --no-cache-dir ./mkdocs-material
 
 ENTRYPOINT ["/sbin/tini", "--"]