Add a missing " to the post install message of install-poetry.py

Author: ruohola

install-poetry.py

@@ -267,7 +267,7 @@ def temporary_directory(*args, **kwargs):
 """
 
 POST_MESSAGE_CONFIGURE_UNIX = """
-Add `export PATH="{poetry_home_bin}:$PATH` to your shell configuration file.
+Add `export PATH="{poetry_home_bin}:$PATH"` to your shell configuration file.
 """
 
 POST_MESSAGE_CONFIGURE_FISH = """