Mjcf : Fix parsing of armature parameters #70

Job	Run time
ubuntu-latest - Env all Release	38m 46s
ubuntu-latest - Env all Debug	41m 19s
ubuntu-latest - Env all-py39 Release	2m 5s
ubuntu-latest - Env all-py39 Debug	3m 41s
macos-latest - Env all Release	1m 31s
macos-latest - Env all Debug	2m 54s
macos-latest - Env all-py39 Release	19m 23s
macos-latest - Env all-py39 Debug	17m 6s
macos-13 - Env all Release	51m 7s
macos-13 - Env all Debug	7m 44s
macos-13 - Env all-py39 Release	4m 57s
macos-13 - Env all-py39 Debug	41m 47s
windows-latest - Env all Release	1h 11m 12s
windows-latest - Env all-clang-cl Release	3m 52s
check-macos-linux-windows-pixi	2s
	5h 7m 26s

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