devcontainer: Install pre-commit using pipx (#704)

Author: jonasbb

.devcontainer/Dockerfile

@@ -3,7 +3,8 @@
 FROM mcr.microsoft.com/devcontainers/rust:1
 
 RUN apt-get update && export DEBIAN_FRONTEND=noninteractive \
-    && apt-get -y install --no-install-recommends lld python3-pip \
+    && apt-get -y install --no-install-recommends lld pipx \
+    && pipx install pre-commit \
     && rustup update \
     && rustup toolchain install nightly --profile minimal --component clippy,rustfmt
 COPY config /root/.cargo/config

.devcontainer/devcontainer.json

@@ -21,7 +21,7 @@
     ],
 
     // Use 'postCreateCommand' to run commands after the container is created.
-    "postCreateCommand": "pip install --user --upgrade pre-commit && pre-commit install --install-hooks",
+    "postCreateCommand": "pre-commit install --install-hooks",
 
     // Comment out connect as root instead. More info: https://aka.ms/vscode-remote/containers/non-root.
     "remoteUser": "root",