Add checksum for Spark 2.4.4 (#293)

Spark 2.4.4 is now the current release
diff --git a/conf/checksums b/conf/checksums
index df1a712..eca9e61 100644
--- a/conf/checksums
+++ b/conf/checksums
@@ -21,6 +21,7 @@
 hadoop:2.7.6:f2327ea93f4bc5a5d7150dee8e0ede196d3a77ff8526a7dd05a48a09aae25669
 hadoop:2.7.5:0bfc4d9b04be919be2fdf36f67fa3b4526cdbd406c512a7a1f5f1b715661f831
 hadoop:2.6.5:001ad18d4b6d0fe542b15ddadba2d092bc97df1c4d2d797381c8d12887691898
+spark:2.4.4:72833745defba95262fbe67306a48c251dbbe17585d65f6095057fc3dc2812ea
 spark:2.4.3:4db62e110c8080f28ac8f1d701b7477cede23e60b51231ab63687b2cc6150faa
 spark:2.3.3:a5c4a54db5163df25110534f36e13d6ae65758d45d1bc8bfcd7e27304e716a23
 spark:2.3.2:3387107155d62f04ccf6bcaf2e00a69a0de5ae5df875348d93147743c206f0a8