build: fix requirements to work with conda

pip treats dashes and underscores the same but conda does not. The package
names here are actually dashes (pip just replaces an underscore with a dash)
so this is more correct anyway.

PR-URL: #800
Reviewed-by: Athan Reines <[email protected]>

Author: asmeurer

doc-requirements.txt

@@ -1,8 +1,8 @@
 sphinx==7.2.6
 sphinx-material==0.0.36
 myst-parser
-sphinx_markdown_tables
-sphinx_copybutton
-sphinx_favicon
+sphinx-markdown-tables
+sphinx-copybutton
+sphinx-favicon
 sphinx-math-dollar
 sphinxcontrib-jquery