remove CONFIG, add fix_qt_plugin_path preference

[cjdoris]

Partially resolves #402

[github-actions]

Benchmark Results (Julia v1)

Time benchmarks

	main	6dbb31d...	main / 6dbb31d...
basic/@py/pydict/init	0.257 ± 0.05 ms	0.245 ± 0.037 ms	1.05 ± 0.26
basic/@py/pydict/pydel	0.258 ± 0.023 ms	0.25 ± 0.029 ms	1.03 ± 0.15
basic/julia/pydict/init	0.221 ± 0.073 ms	0.225 ± 0.076 ms	0.985 ± 0.47
basic/julia/pydict/pydel	0.236 ± 0.042 ms	0.226 ± 0.043 ms	1.05 ± 0.27
gc/full	0.596 ± 0.006 s	0.424 ± 0.0061 s	1.41 ± 0.025
time_to_load	2.08 ± 0.022 s	2.2 ± 0.026 s	0.946 ± 0.015

Memory benchmarks

	main	6dbb31d...	main / 6dbb31d...
basic/@py/pydict/init	5.01 k allocs: 0.0764 MB	5.01 k allocs: 0.0764 MB	1
basic/@py/pydict/pydel	5.01 k allocs: 0.0764 MB	5.01 k allocs: 0.0764 MB	1
basic/julia/pydict/init	4.01 k allocs: 0.0612 MB	4.01 k allocs: 0.0612 MB	1
basic/julia/pydict/pydel	4.01 k allocs: 0.0612 MB	4.01 k allocs: 0.0612 MB	1
gc/full	0 allocs: 0 B	0 allocs: 0 B
time_to_load	0.143 k allocs: 10.6 kB	0.143 k allocs: 10.6 kB	1