fix CI failure

The CI failure of `check-minimal-versions` is caused by this:
- dtolnay/proc-macro2#356
- rust-lang/rust#113152

Not having thiserror pinned at 1.0.2 allow the proc-macro2 crate to be updated to the recent version which fixes this.

Cargo.toml

@@ -34,7 +34,7 @@ rmp-serde = { version = "1.1", optional = true }
 rmpv = { version = "1.0", optional = true, features = ["with-serde"] }
 serde_yaml = { version = "0.9", optional = true }
 serde-pickle = { version = "1.1", optional = true }
-thiserror = "1.0.2"
+thiserror = "1.0"
 async-trait = "0.1.43"
 lapin = { version = "2.1.1", default-features = false }
 log = "0.4"