Fix bullet's cmake_minimum_version warning

extern/CMakeLists.txt

@@ -1,24 +1,32 @@
 set(CMAKE_FOLDER "External")
 include(FetchContent)
 
+# cmake does not feel like fixing this terrible issue in fetchcontent, so we are going to fix it ourselves.
+# solution located here: https://gitlab.kitware.com/cmake/cmake/-/issues/21146#note_933303
+if(NOT WINDOWS)
+    set(BULLET_PATCH_COMMAND git apply -v --ignore-space-change --ignore-whitespace ${CMAKE_CURRENT_SOURCE_DIR}/fix_bullet_cmake_version.patch || true)
+endif()
+
 FetchContent_Declare(
         bullet
         GIT_REPOSITORY https://github.com/bulletphysics/bullet3.git
-        GIT_TAG 2.89
-        CMAKE_ARGS "-Wno-dev"
-        PATCH_COMMAND git apply --ignore-space-change --ignore-whitespace ${CMAKE_CURRENT_SOURCE_DIR}/fix_bullet_cmake_version.patch
+        GIT_TAG fa50f195e6911d60c5ed888d5df33adb1736f93b # v3.21
+        PATCH_COMMAND ${BULLET_PATCH_COMMAND}
+        GIT_SHALLOW ON
 )
 
 FetchContent_Declare(
         spirv-cross
         GIT_REPOSITORY https://github.com/KhronosGroup/SPIRV-Cross.git
         GIT_TAG MoltenVK-1.1.5
+        GIT_PROGRESS TRUE
 )
 
 FetchContent_Declare(
         glslang
         GIT_REPOSITORY https://github.com/KhronosGroup/glslang.git
         GIT_TAG df609a01b386001e367709086c58529c48028d1e # taken from https://github.com/KhronosGroup/SPIRV-Cross/blob/2021-01-15/checkout_glslang_spirv_tools.sh#L3
+        GIT_PROGRESS TRUE
 )
 
 # bullet
@@ -66,7 +74,8 @@ add_subdirectory(doctest)
 
 FetchContent_Declare(json
         GIT_REPOSITORY https://github.com/ArthurSonzogni/nlohmann_json_cmake_fetchcontent.git
-        GIT_TAG v3.9.1)
+        GIT_TAG v3.9.1
+        GIT_PROGRESS TRUE)
 
 FetchContent_GetProperties(json)
 if (NOT json_POPULATED)
@@ -109,6 +118,7 @@ FetchContent_Declare(
         fmt
         GIT_REPOSITORY https://github.com/fmtlib/fmt
         GIT_TAG 8.0.1
+        GIT_PROGRESS TRUE
 )
 
 FetchContent_MakeAvailable(fmt)

extern/fix_bullet_cmake_version.patch

@@ -1,5 +1,4 @@
 diff --git a/CMakeLists.txt b/CMakeLists.txt
-index 68e0a93bc..5b83fb1cd 100644
 --- a/CMakeLists.txt
 +++ b/CMakeLists.txt
 @@ -1,4 +1,4 @@