fix typo in requirements (#300)

Author: mmckerns

docs/requirements.txt

@@ -47,7 +47,7 @@ sphinxcontrib-jquery==4.1
 sphinxcontrib-jsmath==1.0.1
 sphinxcontrib-qthelp==1.0.7
 sphinxcontrib-serializinghtml==1.1.10
-phinxext-opengraph==0.9.1
+sphinxext-opengraph==0.9.1
 starlette==0.40.0
 tomli==2.0.1
 typing-extensions==4.12.1