emboss fails to run on python 3.8

[EricRahm]

Running emboss is currently broken in python version 3.8. I believe our code now relies on at least 3.9 as of PR #111. We could try to add back 3.8 support but given it's EOL in a few months and #111 seems to be fixing a real issue I'd suggest just bumping the min version to 3.9.

STR:

1. Verify the a new default python3 works

# run with local installation
$ python3 --version
Python 3.11.8
$ bazel test \
    'compiler/back_end/cpp:*' \
    'compiler/front_end:*' 'compiler/util:*' 'integration/googletest:*'

<snip>

Executed 80 out of 80 tests: 80 tests pass.
//integration/googletest:emboss_test_util_test                           PASSED in 0.2s

Executed 80 out of 80 tests: 80 tests pass.

2. Explicitly run against python 3.8

$ pyenv install 3.8
$ bazel test --action_env=PYENV_VERSION=3.8 \
    'compiler/back_end/cpp:*' 'compiler/front_end:*' \
    'compiler/util:*' 'integration/googletest:*'

<snip>

//compiler/front_end:write_inference_test                                FAILED in 2.7s
  /usr/local/google/home/erahm/.cache/bazel/_bazel_erahm/ce8d987ff54be8a48c8957a8dbac668b/execroot/com_google_emboss/bazel-out/k8-fastbuild/testlogs/compiler/front_end/write_inference_test/test.log

Executed 80 out of 80 tests: 66 tests pass and 14 fail locally.

$ cat /usr/local/google/home/erahm/.cache/bazel/_bazel_erahm/ce8d987ff54be8a48c8957a8dbac668b/execroot/com_google_emboss/bazel-out/k8-fastbuild/testlogs/compiler/front_end/write_inference_test/test.log
exec ${PAGER:-/usr/bin/less} "$0" || exit 1
Executing tests from //compiler/front_end:write_inference_test
-----------------------------------------------------------------------------
EEEEEEEEEEEEEE
======================================================================
ERROR: test_adds_alias_write_method_to_alias_of_alias_of_physical_field (__main__.WriteInferenceTest)
----------------------------------------------------------------------

<snip>

  File "/tmp/bazel-working-directory/com_google_emboss/bazel-out/k8-fastbuild/bin/compiler/front_end/write_inference_test.runfiles/com_google_emboss/compiler/util/resources.py", line 21, in load
    with importlib.resources.files(
AttributeError: module 'importlib.resources' has no attribute 'files'

3. Explicitly run against 3.9, note things work again

$ pyenv install 3.9
$ bazel test --action_env=PYENV_VERSION=3.9 \
    'compiler/back_end/cpp:*' 'compiler/front_end:*' \
    'compiler/util:*' 'integration/googletest:*'
<snip>
//integration/googletest:emboss_test_util_test                           PASSED in 0.0s

Executed 80 out of 80 tests: 80 tests pass.

[reventlov]

Now obsolete, as Python 3.8 is EOL.