Update pyproject.toml

Fix error from using pinned branch for poetry.  See python-poetry/poetry#6741 and https://github.com/meltano/sdk/blob/main/cookiecutter/target-template/%7B%7Bcookiecutter.target_id%7D%7D/pyproject.toml

pyproject.toml

@@ -31,11 +31,7 @@ multi_line_output = 3 # Vertical Hanging Indent
 src_paths = "target_oracle"
 
 [build-system]
-# Uncomment the pinned version in favor of the git URL once
-# https://github.com/python-poetry/poetry-core/pull/257 is merged
-# and a new poetry-core 1.0.x is released
-# requires = ["poetry-core>=1.0.0"]
-requires = ["poetry-core @ git+https://github.com/python-poetry/poetry-core.git@master"]
+requires = ["poetry-core>=1.0.0"]
 build-backend = "poetry.core.masonry.api"
 
 [tool.poetry.scripts]