Replaced uint16 and uint32 with uint16_t and uint32_t to resolve TIFF deprecations

[radarhere]

When compiling on macOS, deprecation warnings for TIFF have started appearing.

In file included from src/decode.c:491:
src/libImaging/TiffDecode.h:35:5: warning: 'uint32' is deprecated [-Wdeprecated-declarations]
    uint32 ifd; /* offset of the ifd, used for multipage
    ^
/usr/local/Cellar/libtiff/4.3.0/include/tiff.h:84:45: note: 'uint32' has been explicitly marked deprecated here
typedef TIFF_MSC_DEPRECATED uint32_t uint32 TIFF_GCC_DEPRECATED;
                                            ^
/usr/local/Cellar/libtiff/4.3.0/include/tiff.h:66:44: note: expanded from macro 'TIFF_GCC_DEPRECATED'
#define TIFF_GCC_DEPRECATED __attribute__((deprecated))
                                           ^

This is because of https://gitlab.com/libtiff/libtiff/-/merge_requests/205

This PR resolves the warnings by replacing uint16 and uint32 with uint16_t and uint32_t.