Use first version that supported PEP 639

Author: cbrnr

source/shared/build-backend-tabs.rst

@@ -38,5 +38,5 @@
     .. code-block:: toml
 
         [build-system]
-        requires = ["uv_build >= 0.8.0, <0.9.0"]
+        requires = ["uv_build >= 0.7.19, <0.9.0"]
         build-backend = "uv_build"