chore: Fix archlinux dev docker container build (#266)

I'd added some Python dependencies to all the dev docker images in
preparation for actually verifying the Python builds; however the
archlinux dev container build was failing because `pip` is not allowed
on that platforms. This PR replaces the `pip` command with
Archlinux-supplied Python dependencies.
diff --git a/ci/docker/archlinux.dockerfile b/ci/docker/archlinux.dockerfile
index 9446e9a..cc91abb 100644
--- a/ci/docker/archlinux.dockerfile
+++ b/ci/docker/archlinux.dockerfile
@@ -17,9 +17,8 @@
 
 FROM archlinux:latest
 
-RUN pacman -Syu --noconfirm git gcc make cmake r-base gnupg curl arrow python-pip
-
-RUN pip3 install build Cython numpy pytest pyarrow
+RUN pacman -Syu --noconfirm git gcc make cmake r-base gnupg curl arrow \
+    python-pip python-build cython python-numpy python-pytest python-pyarrow
 
 # For R
 RUN mkdir ~/.R && echo "MAKEFLAGS = -j$(nproc)" > ~/.R/Makevars