Make I-miscompile imply I-prioritize

Since I-unsound already implies I-prioritize, it makes sense that I-miscompile should do the same.
diff --git a/triagebot.toml b/triagebot.toml
index 71f1ed0..6f6e95c 100644
--- a/triagebot.toml
+++ b/triagebot.toml
@@ -207,6 +207,7 @@
     "regression-from-stable-to-beta",
     "regression-from-stable-to-nightly",
     "I-unsound",
+    "I-miscompile",
 ]
 exclude_labels = [
     "P-*",