github: Add dependabot configuration and update workflows #16

Job	Run time
docker-platforms (espressif) / docker-arm64 / build-linux/arm64	6m 18s
docker-platforms (nordic) / docker-arm64 / build-linux/arm64	3m 24s
docker-platforms (espressif) / docker-amd64 / build-linux/amd64	6m 26s
docker-platforms (nordic) / docker-amd64 / build-linux/amd64	4m 27s
docker-platforms (nordic) / docker-manifest	14s
docker-platforms (espressif) / docker-manifest	15s
	21m 4s

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