.devcontainer, use python3 instead of python

- see also: c3a27f6d171d7056d82bf1a5a11cd2bcd8d1da31

.devcontainer/Dockerfile

@@ -1,7 +1,7 @@
 FROM ubuntu:rolling
 LABEL maintainer="sgr"
 
-ENV BUILD_DEPS="gnupg gosu libarchive-tools wget curl bzip2 g++ build-essential python git ca-certificates iproute2"
+ENV BUILD_DEPS="gnupg gosu libarchive-tools wget curl bzip2 g++ build-essential python3 git ca-certificates iproute2"
 ENV DEBIAN_FRONTEND=noninteractive
 
 ENV \