added CYX (oxidized CYS) resname in PDB.cpp to ensure compatibility w… #3007

Job	Run time
docker / docker (fedora39)	19m 30s
codecheck / codecheck	43m 23s
conda / conda (ubuntu-20.04)	11m 5s
docker / docker (rocky8)	23m 18s
conda / conda (macos-12)	16m 28s
conda / conda (macos-14)	7m 12s
linux / linux (-doc-mpi-)	40m 12s
mac / macports (macos-12)	15m 3s
linux / linux (-mpi-)	50m 5s
mac / macsimple (macos-12)	9m 23s
mac / macports (macos-14)	9m 9s
linux / linux (-coverage-mpi-)	1h 2m 39s
mac / macsimple (macos-14)	5m 2s
mac / macports (+allmodules, macos-12)	22m 22s
linux / linux (-debug-)	32m 47s
linux / linux (-debug-mpi-)	42m 37s
linux / linux (-intel-)	44m 5s
linux / linux (-pycv-mpi-)	18m 39s
	7h 52m 59s

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