BLD: update minimum Cython version to 3.0.6

Needed to include the bug fix for using complex types with C11
(Cython PR 5809).

Author: rgommers

build_requirements.txt

@@ -1,5 +1,5 @@
 meson-python>=0.13.1
-Cython>=3.0
+Cython>=3.0.6
 ninja
 spin==0.8
 build

meson.build

@@ -33,8 +33,8 @@ elif cc.get_id() == 'msvc'
           'when building with MSVC')
   endif
 endif
-if not cy.version().version_compare('>=0.29.34')
-  error('NumPy requires Cython >= 0.29.34')
+if not cy.version().version_compare('>=3.0.6')
+  error('NumPy requires Cython >= 3.0.6')
 endif
 
 py = import('python').find_installation(pure: false)

pyproject.toml

@@ -2,7 +2,7 @@
 build-backend = "mesonpy"
 requires = [
     "meson-python>=0.15.0",
-    "Cython>=3.0",
+    "Cython>=3.0.6",  # keep in sync with version check in meson.build
 ]
 
 [project]