docs: Minimum required VS version bumped to 16.9

conanfile.py

@@ -88,7 +88,7 @@ class UnitsConan(ConanFile):
                 raise ConanInvalidConfiguration("mp-units requires at least g++-10")
         elif compiler == "Visual Studio":
             if version < "16":
-                raise ConanInvalidConfiguration("mp-units requires at least Visual Studio 16.7")
+                raise ConanInvalidConfiguration("mp-units requires at least Visual Studio 16.9")
         else:
             raise ConanInvalidConfiguration("mp-units is supported only by gcc and Visual Studio so far")
         if compiler.get_safe("cppstd"):

docs/index.rst

@@ -16,7 +16,7 @@ with a permissive `MIT license <https://github.com/mpusz/units/blob/master/LICEN
 .. note::
 
     As this library targets C++23 and extensively uses C++20 features as of now it compiles correctly
-    only with gcc-10, Visual Studio 16.7, and newer.
+    only with gcc-10, Visual Studio 16.9, and newer.
 
 .. toctree::
     :maxdepth: 2

docs/usage.rst

@@ -4,7 +4,7 @@ Usage
 .. note::
 
     This library targets C++23 and extensively uses C++20 features that is why, as of now, it compiles correctly
-    only with gcc-10, Visual Studio 16.7, and newer.
+    only with gcc-10, Visual Studio 16.9, and newer.
 
 Repository Structure and Dependencies
 -------------------------------------