C++17 is needed to compile.

SUMMARY

When I try to compile the latest Git version of kbibtex, I get the error message

```
[ 19%] Building CXX object src/io/CMakeFiles/kbibtexio.dir/encoderlatex.cpp.o
In file included from /usr/include/unicode/unistr.h:39,
                 from /usr/include/unicode/translit.h:27,
                 from /home/ajd/Development/kbibtex/src/io/encoder.cpp:23:
/usr/include/unicode/stringpiece.h:134:23: error: ‘is_same_v’ is not a member of ‘std’; did you mean ‘is_same’?
  134 |                 (std::is_same_v<decltype(T().data()), const char*>
      |                       ^~~~~~~~~
      |                       is_same
/usr/include/unicode/stringpiece.h:134:66: error: template argument 1 is invalid
  134 |                 (std::is_same_v<decltype(T().data()), const char*>
      |                                                                  ^
/usr/include/unicode/stringpiece.h:138:17: error: expected ‘>’ before ‘)’ token
  138 |                 ) &&
      |                 ^
/usr/include/unicode/stringpiece.h:138:17: error: expected unqualified-id before ‘)’ token
In file included from /usr/include/unicode/uenum.h:25,
                 from /usr/include/unicode/utrans.h:22,
                 from /usr/include/unicode/translit.h:29:
/usr/include/unicode/localpointer.h:561:26: error: ‘auto’ parameter not permitted in this context
  561 | template <typename Type, auto closeFunction>
      |                          ^~~~
/usr/include/unicode/localpointer.h:573:76: error: template argument 2 is invalid
  573 |     explicit LocalOpenPointer(std::unique_ptr<Type, decltype(closeFunction)> &&p)
      |                                                                            ^
/usr/include/unicode/localpointer.h:583:78: error: template argument 2 is invalid
  583 |     LocalOpenPointer &operator=(std::unique_ptr<Type, decltype(closeFunction)> &&p) {
      |                                                                              ^
/usr/include/unicode/localpointer.h:599:59: error: template argument 2 is invalid
  599 |     operator std::unique_ptr<Type, decltype(closeFunction)> () && {
      |                                                           ^
/usr/include/unicode/uenum.h:69:1: note: invalid template non-type parameter
   69 | U_DEFINE_LOCAL_OPEN_POINTER(LocalUEnumerationPointer, UEnumeration, uenum_close);
      | ^~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/unicode/uset.h:358:1: note: invalid template non-type parameter
  358 | U_DEFINE_LOCAL_OPEN_POINTER(LocalUSetPointer, USet, uset_close);
      | ^~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/unicode/utrans.h:258:1: note: invalid template non-type parameter
  258 | U_DEFINE_LOCAL_OPEN_POINTER(LocalUTransliteratorPointer, UTransliterator, utrans_close);
      | ^~~~~~~~~~~~~~~~~~~~~~~~~~~
[ 19%] Building CXX object src/io/CMakeFiles/kbibtexio.dir/fileexporterbibtex2html.cpp.o
make[2]: *** [src/io/CMakeFiles/kbibtexio.dir/build.make:99: src/io/CMakeFiles/kbibtexio.dir/encoder.cpp.o] Error 1
make[2]: *** Waiting for unfinished jobs....
make[1]: *** [CMakeFiles/Makefile2:1598: src/io/CMakeFiles/kbibtexio.dir/all] Error 2
make: *** [Makefile:146: all] Error 2
```

STEPS TO REPRODUCE
1. 
2. 
3. 

OBSERVED RESULT


EXPECTED RESULT


SOFTWARE/OS VERSIONS
Linux/KDE Plasma: Archlinux
Qt Version:  5.15.15

ADDITIONAL INFORMATION

Changing "14" to "17" on line 16 of CMakeLists.txt fixes this.