CMake: update minimum cmake version to avoid warnings

CMake 3.27 issued a deprecation warning saying cmake <3.5 would no longer
be supported.

closes adishavit#86

CMakeLists.txt

@@ -1,4 +1,4 @@
-cmake_minimum_required(VERSION 3.1)
+cmake_minimum_required(VERSION 3.5)
 
 project(argh)
 
@@ -16,39 +16,39 @@ option(BUILD_EXAMPLES "Build examples. Uncheck for install only runs"
        ${ARGH_MASTER_PROJECT})
 
 if (CMAKE_CXX_COMPILER_ID MATCHES "(Clang|GNU)")
-	list(APPEND flags "-Wall" "-Wextra" "-Wshadow" "-Wnon-virtual-dtor" "-pedantic")
+    list(APPEND flags "-Wall" "-Wextra" "-Wshadow" "-Wnon-virtual-dtor" "-pedantic")
 elseif(MSVC)
-	list(APPEND flags "/W4" "/WX")
+    list(APPEND flags "/W4" "/WX")
 endif()
 
 if(BUILD_EXAMPLES)
-	add_executable(argh_example example.cpp)
-	target_compile_options(argh_example PRIVATE ${flags})
+    add_executable(argh_example example.cpp)
+    target_compile_options(argh_example PRIVATE ${flags})
 endif()
 if(BUILD_TESTS)
-	add_executable(argh_tests   argh_tests.cpp)
-	target_compile_options(argh_tests PRIVATE ${flags})
-	set_property(DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR} PROPERTY VS_STARTUP_PROJECT argh_tests)
+    add_executable(argh_tests   argh_tests.cpp)
+    target_compile_options(argh_tests PRIVATE ${flags})
+    set_property(DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR} PROPERTY VS_STARTUP_PROJECT argh_tests)
 endif()
 
 add_library(argh INTERFACE)
 target_include_directories(argh INTERFACE $<BUILD_INTERFACE:${CMAKE_CURRENT_LIST_DIR}> $<INSTALL_INTERFACE:include>)
 
 if(ARGH_MASTER_PROJECT)
-	install(TARGETS argh EXPORT arghTargets)
-
-	include(GNUInstallDirs)
-	install(FILES "${CMAKE_CURRENT_LIST_DIR}/argh.h" DESTINATION ${CMAKE_INSTALL_INCLUDEDIR})
-	install(FILES "${CMAKE_CURRENT_LIST_DIR}/LICENSE" DESTINATION ${CMAKE_INSTALL_DOCDIR})
-	install(FILES "${CMAKE_CURRENT_LIST_DIR}/README.md" DESTINATION ${CMAKE_INSTALL_DOCDIR})
-
-	if(APPLE OR CMAKE_SYSTEM_NAME STREQUAL Linux)
-	# this might be a bit too restrictive, since for other (BSD, ...) this might apply also
-	# but this can be fixed later in extra pull requests from people on the platform
-		install(FILES argh-config.cmake DESTINATION ${CMAKE_INSTALL_LIBDIR}/cmake/argh)
-		install(EXPORT arghTargets DESTINATION ${CMAKE_INSTALL_LIBDIR}/cmake/argh)
-	else()
-		install(FILES argh-config.cmake DESTINATION CMake)
-		install(EXPORT arghTargets DESTINATION CMake)
-	endif()
+    install(TARGETS argh EXPORT arghTargets)
+
+    include(GNUInstallDirs)
+    install(FILES "${CMAKE_CURRENT_LIST_DIR}/argh.h" DESTINATION ${CMAKE_INSTALL_INCLUDEDIR})
+    install(FILES "${CMAKE_CURRENT_LIST_DIR}/LICENSE" DESTINATION ${CMAKE_INSTALL_DOCDIR})
+    install(FILES "${CMAKE_CURRENT_LIST_DIR}/README.md" DESTINATION ${CMAKE_INSTALL_DOCDIR})
+
+    if(APPLE OR CMAKE_SYSTEM_NAME STREQUAL Linux)
+    # this might be a bit too restrictive, since for other (BSD, ...) this might apply also
+    # but this can be fixed later in extra pull requests from people on the platform
+        install(FILES argh-config.cmake DESTINATION ${CMAKE_INSTALL_LIBDIR}/cmake/argh)
+        install(EXPORT arghTargets DESTINATION ${CMAKE_INSTALL_LIBDIR}/cmake/argh)
+    else()
+        install(FILES argh-config.cmake DESTINATION CMake)
+        install(EXPORT arghTargets DESTINATION CMake)
+    endif()
 endif()