Change package hash in curl.mk to lower case because of BusyBox case sensitivity.
Change package hash in curl.mk to lower case because of BusyBox case sensitivity.

Co-authored-by: Cy Rossignol <31ace4ad1831aae866cd7951a842ca3e38f21981@rossignols.me>
caraka/gridcoinresearch,gridcoin/Gridcoin-Research,gridcoin/Gridcoin-Research,caraka/gridcoinresearch,gridcoin/Gridcoin-Research,caraka/gridcoinresearch,Git-Jiro/Gridcoin-Research,caraka/gridcoinresearch,Git-Jiro/Gridcoin-Research,gridcoin/Gridcoin-Research,caraka/gridcoinresearch,caraka/gridcoinresearch,Git-Jiro/Gridcoin-Research,Git-Jiro/Gridcoin-Research,gridcoin/Gridcoin-Research,gridcoin/Gridcoin-Research,Git-Jiro/Gridcoin-Research