convert : fix broken sentencepiece vocab (#14416) #1

Job	Run time
macOS-x64	17s
macOS-arm64	18s
ubuntu-22-cpu (x64, ubuntu-22.04)	19s
ubuntu-22-vulkan	19s
windows-hip (radeon, gfx1100;gfx1101;gfx1102;gfx1030;gfx1031;gfx1032)	20s
windows-sycl	33s
windows-cpu (x64)	20s
ios-xcode-build	30s
windows-cpu (arm64)	21s
windows (opencl-adreno, arm64, -G "Ninja Multi-Config" -D CMAKE_TOOLCHAIN_FILE=cmake/arm64-window...	20s
windows (vulkan, x64, -DGGML_VULKAN=ON, ggml-vulkan)	28s
windows-cuda (12.4)	20s
release	1s
	4m 26s

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