Add typing-extension as dependency

Author: SamProkopchuk

poetry.lock

@@ -19,13 +19,14 @@ tqdm = "~4"
 ipywidgets = "~7"
 ipython = "*"
 ibm-cos-sdk = {version = "~2", optional = true}
+typing-extensions = {version = "*", python = "^3.5", optional = true}
 # Sphinx documentation dependencies
 Sphinx = { version = "~4", optional = true }
 sphinx-autodoc-typehints = { version = "~1", optional = true }
 pydata-sphinx-theme = { version = "~0.9", optional = true }
 
 [tool.poetry.extras]
-regular = ["ibm-cos-sdk"]
+regular = ["ibm-cos-sdk", "typing-extensions"]
 docs = ["Sphinx", "sphinx-autodoc-typehints", "pydata-sphinx-theme"]
 
 [tool.poetry.dev-dependencies]