CompatHelper: bump compat for LLVM to 7, (keep existing compat) (#532)

Co-authored-by: CompatHelper Julia <compathelper_noreply@julialang.org>

Author: github-actions[bot]

Project.toml

@@ -16,7 +16,7 @@ Statistics = "10745b16-79ce-11e8-11f9-7d13ad32a3b2"
 [compat]
 Adapt = "4.0"
 GPUArraysCore = "= 0.1.6"
-LLVM = "3.9, 4, 5, 6"
+LLVM = "3.9, 4, 5, 6, 7"
 LinearAlgebra = "1"
 Printf = "1"
 Random = "1"