Update syn requirement from 1.0.95 to 2.0.15 (#153)

Updates the requirements on [syn](https://github.com/dtolnay/syn) to permit the latest version.
- [Release notes](https://github.com/dtolnay/syn/releases)
- [Commits](dtolnay/syn@1.0.95...2.0.15)

---
updated-dependencies:
- dependency-name: syn
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

duckdb-loadable-macros/Cargo.toml

@@ -16,7 +16,7 @@ description = "Native bindings to the libduckdb library, C API; build loadable e
 [dependencies]
 proc-macro2 = { version = "1.0.56" }
 quote = { version = "1.0.21" }
-syn = { version = "1.0.95", features = [ "extra-traits", "full", "fold", "parsing" ] }
+syn = { version = "2.0.15", features = [ "extra-traits", "full", "fold", "parsing" ] }
 
 [lib]
 proc-macro = true