Fixed once_cell at v0.14

Author: Andrew J Westlake

Cargo.toml

@@ -114,7 +114,7 @@ async-channel = { version = "1.6", optional = true }
 clap = { version = "3.1.5", optional = true }
 futures = "0.3"
 inventory = { version = "0.3", optional = true }
-once_cell = "1.14"
+once_cell = "=1.14"
 pin-project-lite = "0.2"
 pyo3 = "0.17"
 pyo3-asyncio-macros = { path = "pyo3-asyncio-macros", version = "=0.17.0", optional = true }