doc: update requirements

breathe: for simplicity, require versions > 4.30 (lower versions have
known issues, so do not take risks).
Sphinx: start requiring versions >=4.x. Keep with compatible versions,
since Sphinx major updrages can easily break extensions, themes, etc.
sphinx_rtd_theme: upgrade to >=1.x. Again, keep with compatible versions
since we have style customizations that can likely break on major
upgrades.
pygments: Allow any version >=2.9 (version that introduced DT support).
We do not have strong compatibility requirements here.
sphinx-notfound-page: Remove any requirements, we do not have strong
requirements for this one.

Signed-off-by: Gerard Marull-Paretas <gerard.marull@nordicsemi.no>
diff --git a/scripts/requirements-doc.txt b/scripts/requirements-doc.txt
index b11f809..650f555 100644
--- a/scripts/requirements-doc.txt
+++ b/scripts/requirements-doc.txt
@@ -1,12 +1,12 @@
 # DOC: used to generate docs
 
-breathe~=4.23,!=4.29.0
-sphinx~=3.3
-sphinx_rtd_theme>=0.5.2,<1.0
+breathe>=4.30
+sphinx~=4.0
+sphinx_rtd_theme~=1.0
 sphinx-tabs
 sphinxcontrib-svg2pdfconverter
-pygments~=2.9
-sphinx-notfound-page>=0.6
+pygments>=2.9
+sphinx-notfound-page
 
 # YAML validation. Used by zephyr_module.
 PyYAML>=5.1