Bump LLVM version

MasonProtter · web-flow · commit 59efe6e0814a · 2022-02-24T16:17:11.000-07:00
This should fix the breakages that happened on the MacOS master builds
diff --git a/Project.toml b/Project.toml
@@ -12,7 +12,7 @@ Serialization = "9e88b42a-f829-5b0c-bbe9-9e923198166b"
 
 [compat]
 GPUCompiler = "0.13"
-LLVM = "4"
+LLVM = "4.8"
 julia = "1.7"
 
 [extras]
