remove core2 dependencies

Author: stevefan1999-personal

Cargo.toml

@@ -16,7 +16,6 @@ base64 = { version = "0.13.0", default-features = false }
 base64-simd = { version = "0.5.0", default-features = false, optional = true }
 byteorder = { version = "1.4.3", default-features = false }
 cfg-if = "1.0.0"
-core2 = "0.4.0"
 heapless = "0.7.14"
 httparse = { version = "1.7.1", default-features = false }
 rand_core = "0.6.3"