Make Django image use Python 3.10

[MarkusH]

Django 5.0 will require Python 3.10 or newer. The current Python base image seems to only have Python 3.8 available.

Starting Step #3 - "compile-libfuzzer-address-x86_64"
Step #3 - "compile-libfuzzer-address-x86_64": Already have image (with digest): gcr.io/cloud-builders/docker
Step #3 - "compile-libfuzzer-address-x86_64": ---------------------------------------------------------------
Step #3 - "compile-libfuzzer-address-x86_64": Compiling libFuzzer to /usr/lib/libFuzzingEngine.a...  done.
Step #3 - "compile-libfuzzer-address-x86_64": ---------------------------------------------------------------
Step #3 - "compile-libfuzzer-address-x86_64": CC=clang
Step #3 - "compile-libfuzzer-address-x86_64": CXX=clang++
Step #3 - "compile-libfuzzer-address-x86_64": CFLAGS=-O1 -fno-omit-frame-pointer -gline-tables-only -DFUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION -fsanitize=address -fsanitize-address-use-after-scope -fsanitize=fuzzer-no-link -fno-sanitize=function,leak,vptr,
Step #3 - "compile-libfuzzer-address-x86_64": CXXFLAGS=-O1 -fno-omit-frame-pointer -gline-tables-only -DFUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION -fsanitize=address -fsanitize-address-use-after-scope -fsanitize=fuzzer-no-link -stdlib=libc++ -fno-sanitize=function,leak,vptr
Step #3 - "compile-libfuzzer-address-x86_64": RUSTFLAGS=--cfg fuzzing -Zsanitizer=address -Cdebuginfo=1 -Cforce-frame-pointers
Step #3 - "compile-libfuzzer-address-x86_64": ---------------------------------------------------------------
Step #3 - "compile-libfuzzer-address-x86_64": + pip3 install .
Step #3 - "compile-libfuzzer-address-x86_64": Processing /src/django
Step #3 - "compile-libfuzzer-address-x86_64":   Installing build dependencies ... done
Step #3 - "compile-libfuzzer-address-x86_64":   Getting requirements to build wheel ... done
Step #3 - "compile-libfuzzer-address-x86_64":   Installing backend dependencies ... done
Step #3 - "compile-libfuzzer-address-x86_64":     Preparing wheel metadata ... done
Step #3 - "compile-libfuzzer-address-x86_64": ERROR: Package 'Django-5.0.dev20230207193000' requires a different Python: 3.8.3 not in '>=3.10'
Step #3 - "compile-libfuzzer-address-x86_64": WARNING: You are using pip version 19.2.3, however version 23.0 is available.
Step #3 - "compile-libfuzzer-address-x86_64": You should consider upgrading via the 'pip install --upgrade pip' command.
Step #3 - "compile-libfuzzer-address-x86_64": ********************************************************************************
Step #3 - "compile-libfuzzer-address-x86_64": Failed to build.
Step #3 - "compile-libfuzzer-address-x86_64": To reproduce, run:
Step #3 - "compile-libfuzzer-address-x86_64": python infra/helper.py build_image django
Step #3 - "compile-libfuzzer-address-x86_64": python infra/helper.py build_fuzzers --sanitizer address --engine libfuzzer --architecture x86_64 django
Step #3 - "compile-libfuzzer-address-x86_64": ********************************************************************************
Finished Step #3 - "compile-libfuzzer-address-x86_64"
ERROR
ERROR: build step 3 "gcr.io/cloud-builders/docker" failed: step exited with non-zero status: 1