📌 Pin project's dependencies

- Freeze sphinx-copybutton version number.
- Normalize package names to use dashes (-) as separators between words
in the package name. This is the canonical format for package names on PyPI.

requirements.txt

@@ -1,4 +1,4 @@
 sphinx==5.3.0
-sphinx_rtd_theme==1.2.0
-sphinx_copybutton
-myst_parser==0.18.1
+sphinx-rtd-theme==1.2.0
+sphinx-copybutton==0.5.2
+myst-parser==0.18.1