Workbench: Install PDM and plugins using pipx.

This way they don't conflict with anything else.

workbench/Dockerfile

@@ -203,7 +203,6 @@ RUN apt-get update && \
         parse \
         passhole \
         passlib \
-        pdm \
         pgcli \
         pip-tools \
         pipenv \
@@ -232,7 +231,8 @@ RUN apt-get update && \
         transmission-rpc \
         ziglang \
     && \
-    echo pdm-version | xargs -tn1 pdm plugin add --pip-args=--break-system-packages && \
+    pipx install pdm && \
+    pipx inject pdm pdm-version pdm-packer pdm-publish && \
     npm install --global \
         corepack \
         @playwright/test \