feat(doc): geonature version is retrieved from the VERSION file

docs/conf.py

@@ -20,6 +20,9 @@
 import sys, os
 
 sys.path.insert(0, os.path.abspath("../backend"))
+from pathlib import Path
+
+VERSION_GN = Path(__file__).resolve().parent.parent.joinpath("VERSION").read_text().strip()
 
 # -- General configuration ------------------------------------------------
 
@@ -73,9 +76,9 @@
 # built documents.
 #
 # The short X.Y version.
-version = "2.15.0"
+version = VERSION_GN
 # The full version, including alpha/beta/rc tags.
-release = "2.15.0"
+release = VERSION_GN
 
 # The language for content autogenerated by Sphinx. Refer to documentation
 # for a list of supported languages.