[cmake] bump minimal cxx standard, fix build type caching

Author: renefritze

.ci/azure-pipelines.yml

@@ -13,4 +13,5 @@ strategy:
 container: $[ variables['containerImage'] ]
 
 steps:
-- script: ./.ci/travis.script.bash
+- script: ./.ci/pytest.bash
+- script: ./.ci/wheel.bash

.ci/common_setup.bash

@@ -19,4 +19,4 @@ python -m venv ~/venv
 source ~/venv/bin/activate
 python -m pip install -U pip pytest wheel
 
-python -m install git+https://github.com/pymor/pymor.git#egg=pymor
+python -m pip install git+https://github.com/pymor/pymor.git#egg=pymor

.ci/pytest.bash

@@ -1,7 +1,7 @@
-cmake_minimum_required(VERSION 2.8.12)
+cmake_minimum_required(VERSION 3.2)
 
 # this should only be necessary while the deal setup macro is copied
-set(CMAKE_CXX_STANDARD 14 CACHE STRING "")
+set(CMAKE_CXX_STANDARD 17 CACHE STRING "")
 
 project(pymor_dealii)
 
@@ -10,7 +10,7 @@ INCLUDE(dealii_macro)
 # Set a default build configuration if none is specified. 'MinSizeRel' produces the smallest binaries
 if(NOT CMAKE_BUILD_TYPE AND NOT CMAKE_CONFIGURATION_TYPES)
   message(STATUS "Setting build type to 'RelWithDebInfo' as none was specified.")
-  set(CMAKE_BUILD_TYPE RelWithDebInfo STRING "Choose the type of build." FORCE)
+  set(CMAKE_BUILD_TYPE RelWithDebInfo CACHE STRING "Choose the type of build." FORCE)
 endif()
 # Add a CMake parameter for choosing a desired Python version
 set(PYBIND11_PYTHON_VERSION "3" CACHE STRING "Python version to use for compiling the example library")