fix: compilation of test dep 'mysql-connector-c 5.7' in newer CMake (> 4)

Compilation for 'mysql-connector-c' for 5.7 is broken in newer CMake
versions. There is no simple around this, since CMake 4 introduces
multiple breaking changes and 'CMAKE_POLICY_VERSION_MINIMUM' isn't
sufficient to fix this issues.

Due to this, the simplest fix is to install in the testing environment
CMake3. This fixed version of CMake should be used specifically for
building this dependency. Arch Linux has a package that could be used as
reference https://aur.archlinux.org/packages/cmake3.

test/deps/Makefile

@@ -53,7 +53,10 @@ ifeq ($(UNAME_S),Darwin)
 	cd mysql-connector-c/mysql-connector-c && cmake . -DWITH_BOOST=./boost -DCMAKE_BUILD_TYPE=RelWithDebInfo -DCMAKE_CXX_FLAGS_RELWITHDEBINFO="-O0 -ggdb -DNDEBUG -fPIC" -DCMAKE_POLICY_VERSION_MINIMUM=3.5 -DWITH_SSL=$$(brew --prefix openssl@3) -DOPENSSL_ROOT_DIR=$$(brew --prefix openssl@3)
 else
 	cd mysql-connector-c && ln -fsT $$(ls -1d mysql-5.7.*/) mysql-connector-c
-	cd mysql-connector-c/mysql-connector-c && cmake . -DWITH_BOOST=./boost -DCMAKE_BUILD_TYPE=RelWithDebInfo -DCMAKE_CXX_FLAGS_RELWITHDEBINFO="-O0 -ggdb -DNDEBUG -fPIC" -DCMAKE_POLICY_VERSION_MINIMUM=3.5
+	cd mysql-connector-c/mysql-connector-c && cmake3 . -DWITH_BOOST=./boost \
+		-DCMAKE_BUILD_TYPE=RelWithDebInfo -DCMAKE_C_FLAGS="-Wno-incompatible-pointer-types" \
+		-DCMAKE_CXX_FLAGS_RELWITHDEBINFO="-O0 -ggdb -DNDEBUG -fPIC -Wno-incompatible-pointer-types" \
+		-DCMAKE_POLICY_VERSION_MINIMUM=3.5
 endif
 ifeq ($(UNAME_S),Darwin)
 	cd mysql-connector-c/mysql-connector-c && CC=${CC} CXX=${CXX} ${MAKE} -j1 mysqlclient mysql