Update Dockerfile

Dockerfile

@@ -29,11 +29,10 @@ run ~/miniconda3/bin/conda env create -f ./env.yml
 
 run git lfs install --force
 run git clone https://github.com/python/cpython
-run cd cpython
-run ./configure --enable-optimizations --with-lto --prefix=$HOME/python
-run make
-run make install
-run PATH="$HOME/python${PATH:+:${PATH}}"
+run cd cpython && ./configure --enable-optimizations --with-lto --prefix=$HOME/python
+run cd cpython && make
+run cd cpython && make install
+run PATH="${PATH:+${PATH}:}$HOME/python"
 
 run python -m pip install --upgrade --no-cache-dir pip
 run python -m pip install --upgrade --no-cache-dir -r deps.txt