Update cmake requirement version (#4100)

Summary:
X-link: facebookresearch/FBGEMM#1184


Update the fbgemm minimum CMake version required to 3.21
This is to support updating fbgemm pinned version in PyTorch D74335570

Differential Revision: D74434751

Author: gchalump

CMakeLists.txt

@@ -10,7 +10,7 @@
 
 # A minimum CMake version of 3.21+ is needed to support the required C and C++
 # standard versions
-cmake_minimum_required(VERSION 3.25 FATAL_ERROR)
+cmake_minimum_required(VERSION 3.21 FATAL_ERROR)
 
 list(APPEND CMAKE_MODULE_PATH "${CMAKE_CURRENT_SOURCE_DIR}/cmake/modules")
 

bench/CMakeLists.txt

@@ -4,7 +4,7 @@
 # This source code is licensed under the BSD-style license found in the
 # LICENSE file in the root directory of this source tree.
 
-cmake_minimum_required(VERSION 3.25 FATAL_ERROR)
+cmake_minimum_required(VERSION 3.21 FATAL_ERROR)
 
 set(CMAKE_CXX_STANDARD 20)
 set(CMAKE_CXX_EXTENSIONS OFF)

fbgemm_gpu/CMakeLists.txt

@@ -8,7 +8,7 @@
 # CMake Prelude
 ################################################################################
 
-cmake_minimum_required(VERSION 3.25 FATAL_ERROR)
+cmake_minimum_required(VERSION 3.21 FATAL_ERROR)
 
 set(CMAKEMODULES ${CMAKE_CURRENT_SOURCE_DIR}/../cmake/modules)
 set(FBGEMM_GPU ${CMAKE_CURRENT_SOURCE_DIR})

test/CMakeLists.txt

@@ -4,7 +4,7 @@
 # This source code is licensed under the BSD-style license found in the
 # LICENSE file in the root directory of this source tree.
 
-cmake_minimum_required(VERSION 3.25 FATAL_ERROR)
+cmake_minimum_required(VERSION 3.21 FATAL_ERROR)
 
 set(CMAKE_CXX_STANDARD 20)
 set(CMAKE_CXX_EXTENSIONS OFF)