Fix compile

[372046933]

Before:

➜ cqueue git:(main) make tests
c++ -g -std=c++20 -Wall -Wextra -Wpedantic -Wconversion -Wsign-conversion -Wnull-dereference -Weffc++ -o cqueue-tests cqueue-tests.cpp
In file included from cqueue-tests.cpp:6:
./cqueue.hpp:586:11: error: missing 'typename' prior to dependent type name 'gto::cqueue<T, Allocator>::value_type'
constexpr gto::cqueue<T, Allocator>::value_type gto::cqueue<T, Allocator>::pop_front() {
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
typename ./cqueue.hpp:599:11: error: missing 'typename' prior to dependent type name 'gto::cqueue<T, Allocator>::value_type'
constexpr gto::cqueue<T, Allocator>::value_type gto::cqueue<T, Allocator>::pop_back() {
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
typename 2 errors generated.
make: *** [tests] Error 1

After:

➜ cqueue git:(main) ✗ make tests
c++ -g -std=c++20 -Wall -Wextra -Wpedantic -Wconversion -Wsign-conversion -Wnull-dereference -Weffc++ -o cqueue-tests cqueue-tests.cpp
./cqueue-tests
===============================================================================
All tests passed (592 assertions in 1 test case)

[torrentg]

Thank you for your contribution.