remove julia mention in dev guide

doc/development/development_guide.rst

@@ -37,13 +37,6 @@ using development mode:
 The ``-e`` flag ensures that edits to the source code will be reflected when
 importing Mr Mustard in Python.
 
-Increased numerical stability using Julia [optional]
-------------------
-Converting phase space objects to Fock space can be numerically unstable due to accumulating floating point errors.
-To resolve this, the conversion can be performed with extended-precision arithmetic. To use this feature,
-an installation of `Julia <https://github.com/JuliaLang/juliaup#installation>`_ is required (version 1.9.3 recommended).
-If no valid version of Julia is found, it will be installed automatically before trying to run any Julia code.
-
 Development environment
 -----------------------