Cargo.toml: use resolver version 2

newAM · newAM · commit 78ed782d5936 · 2022-03-21T12:07:47.000-07:00
Virtual workspaces still need to set this manually, even when using
edition 2021.
diff --git a/Cargo.toml b/Cargo.toml
@@ -1,4 +1,5 @@
 [workspace]
+resolver = "2"
 members = [
     "*-bsp",
     "examples",
