patch_inplace assumes StringType is std::string

Description

patch_inplace has several instances of get<std::string>, which breaks the build if you're using a custom string.

Reproduction steps

Instantiate a nlohmann::basic_json<> with a custom string type
Attempt to call nlohmann:basic_json<>::patch

Expected vs. actual results

Compilation fails.

Minimal code example

struct MyString;  // some compatible impl

using Value = nlohmann::basic_json<
        std::map,
        std::vector,
        MyString,
        bool,
        std::int64_t,
        std::uint64_t,
        double,

        std::allocator,
        nlohmann::adl_serializer,
        std::vector<std::uint8_t>
>;

Value base, patch;
base.patch(patch);

Error messages

No matching constructor for initialization of 'nlohmann::basic_json<std::map, std::vector, MyString >::json_pointer' (aka 'json_pointer< MyString >')

Compiler and operating system

Apple clang version 14.0.3 (clang-1403.0.22.14.1), macOS Ventura 13.5.1

Library version

3.11.2

Validation

[X] The bug also occurs if the latest version from the develop branch is used.
[X] I can successfully compile and run the unit tests.

nlohmann / json

patch_inplace assumes StringType is std::string #4134