feat: allow blst 0.3.10 *or newer* (#58)

Some dependents of blstrs might require newer versions of `blst`. Try to
relax the requirements of `blst` and allow 0.3.10 or newer (instead of
pinning it to 0.3.10 only).

Cargo.toml

@@ -15,7 +15,7 @@ rust-version = "1.56.1"
 rustdoc-args = [ "--html-in-header", "katex-header.html" ]
 
 [dependencies]
-blst = { version = "=0.3.10", default-features = true }
+blst = { version = "0.3.10", default-features = true }
 rand_core = "0.6"
 ff = "0.13"
 group = { version = "0.13", features = ["tests"] }