fix: license file detection according to PEP621 #1895

Job	Run time
StaticCodingAnalysis (py3.13 -current)	55s
StaticCodingAnalysis (py3.9 -lowest)	45s
install & run "cyclonedx-py --help" (ubuntu-latest)	14s
install & run "python -m cyclonedx_py --help" (ubuntu-latest)	11s
install & run "python -m cyclonedx_py --help" (macos-latest)	34s
install & run "cyclonedx-py --help" (windows-latest)	31s
install & run "cyclonedx-py --help" (macos-latest)	31s
install & run "python -m cyclonedx_py --help" (windows-latest)	38s
find Upgradable CodingFeatures	46s
find Security Issues	44s
Test (macos-latest py3.13)	2m 32s
Test (ubuntu-latest py3.10)	2m 49s
Test (ubuntu-latest py3.9)	2m 38s
Test (macos-latest py3.12)	2m 11s
Test (ubuntu-latest py3.12)	2m 43s
Test (ubuntu-latest py3.11)	2m 29s
Test (windows-latest py3.10)	4m 15s
Test (windows-latest py3.11)	4m 24s
Test (macos-latest py3.11)	2m 42s
Test (macos-13 py3.10)	4m 23s
Test (windows-latest py3.9)	3m 56s
Test (ubuntu-latest py3.13)	2m 52s
Test (windows-latest py3.13)	4m 25s
Test (macos-13 py3.9)	4m 0s
Test (windows-latest py3.12)	4m 28s
Linting & Coding Standards	36s
Publish test coverage	30s
	57m 42s

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