Move secret mounting further up

Dockerfile

@@ -1,9 +1,15 @@
 FROM python:3.10
 
+# Get secret DB_URL and output it to /test at buildtime
+RUN --mount=type=secret,id=DB_URL,mode=0444,required=true \
+   cat /run/secrets/DB_URL > /test
+
 # Set up a new user named "user" with user ID 1000
 RUN useradd -m -u 1000 user
+
 # Switch to the "user" user
 USER user
+
 # Set home to the user's home directory
 ENV HOME=/home/user \
 	PATH=/home/user/.local/bin:$PATH
@@ -14,10 +20,6 @@ WORKDIR $HOME/app
 # Copy the current directory contents into the container at $HOME/app setting the owner to the user
 COPY --chown=user . $HOME/app
 
-# Get secret DB_URL and output it to /test at buildtime
-RUN --mount=type=secret,id=DB_URL,mode=0444,required=true \
-   cat /run/secrets/DB_URL > /test
-
 RUN pip install --no-cache-dir poetry
 
 RUN poetry install --only main