Update slang digest to a15be31

Author: renovate[bot]

WORKSPACE

@@ -55,10 +55,10 @@ http_archive(
     name = "slang",
     build_file = "slang.BUILD",
     patches = ["//external:slang.patch"],
-    sha256 = "eea4b20751fa6394647330518c9b0c46c8248fea984c91a8a8bfe01a8a04567e",
-    strip_prefix = "slang-458be618a58aa1896398eccc1ddf75b880afaab6",
+    sha256 = "328e83bdf8541ed3a0138b252ab9c1bfee95a3e34161b6ffa0e9364caf6e9419",
+    strip_prefix = "slang-a15be31aad05c0d2e2909d3b5696d0b53898817b",
     urls = [
-        "https://github.com/MikePopoloski/slang/archive/458be618a58aa1896398eccc1ddf75b880afaab6.zip",
+        "https://github.com/MikePopoloski/slang/archive/a15be31aad05c0d2e2909d3b5696d0b53898817b.zip",
     ],
 )