Fix "play build-module" by replacing yaml.load with yaml.safe_load

[davidcostanzo]

This fixes an error when "play build-module" is run on Python 3.7.11

load() missing 1 required positional argument: 'Loader'

This follows the recommendation shown on
https://github.com/yaml/pyyaml/wiki/PyYAML-yaml.load(input)-Deprecation

A loader argument is now required. This commit assumes that dependencies.yml uses standard YAML tags, and so uses safe_loader. This is the most secure loader.

Helpful things

Fixes

Fixes #1456

Purpose

This pull request fixes a bug where "play build-module" throws an error with Python 3.7.11

Traceback (most recent call last):
  File "/devel/dcostanz/github/play1_david_costanzo/play", line 168, in <module>
    status = cmdloader.commands[play_command].execute(command=play_command, app=play_app, args=remaining_args, env=play_env, cmdloader=cmdloader)
  File "/scharp/devel/dcostanz/github/play1_david_costanzo/framework/pym/play/commands/modulesrepo.py", line 73, in execute
    build(app, args, env)
  File "/scharp/devel/dcostanz/github/play1_david_costanzo/framework/pym/play/commands/modulesrepo.py", line 331, in build
    deps = yaml.load(f.read())

With Python 3.10.12, it's merely a warning

~ calling yaml.load() without Loader=... is deprecated, as the default Loader is unsafe. Please read https://msg.pyyaml.org/load for full details.