Add OpenCV DNN pipeline #3012

Job	Run time
photon-build-all	43s
Build Examples	55s
photonclient-build	59s
photonclient-check-lint	29s
Photonlib - Build Host - Win64	1m 45s
photonserver-build-offline-docs	1m 3s
photonserver-check-lint	58s
Photonlib - Build Host - Linux	3m 14s
Photonlib - Build Docker - Athena	1m 28s
Photonlib - Build Docker - Raspbian	1m 41s
Photonlib - Build Docker - Aarch64	3m 51s
wpiformat	24s
Build fat JAR - ${{ matrix.artifact-name }}	0s
Build image - ${{ matrix.image_url }}	0s
photon-release	0s
	17m 30s

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