Use specific blockfrost-python version

Since blockfrost-python is still under beta development, any minor or patch version could be backward incompatible. We will use a certain blockfrost version until its first major version has been released.

Author: cffls

pyproject.toml

@@ -25,7 +25,7 @@ python = "^3.7"
 PyNaCl = "^1.4.0"
 cbor2 = "^5.4.2"
 typeguard = "^2.13.3"
-blockfrost-python = "^0.4.4"
+blockfrost-python = "0.4.4"
 websocket-client = "^1.2.3"
 
 [tool.poetry.dev-dependencies]