Mark rules_pkg as a dev dependency #4

Job	Run time
build	9m 12s
package (macos-14, darwin_arm64, dist_zip)	9m 7s
package (macos-14-large, darwin_x86_64, dist_zip)	3s
package (windows-2022, x64_windows, dist_zip)	15m 11s
package (windows-2022, x64_x86_windows, dist_zip)	14m 34s
	48m 7s

Provide feedback