[release] v0.7.27

[Leonz5288]

Full changelog:

• [Lang] Support very basic python string.format() now ([Lang] Support very basic python string.format() now #2552) (by Jiasheng Zhang)
• [vulkan] Add a simple memory allocator ([vulkan] Add a simple memory allocator #2556) (by Ye Kuang)
• [vulkan] Add Vulkan struct compiler and some helpers ([vulkan] Add Vulkan struct compiler and some helpers #2550) (by Ye Kuang)
• [autodiff] Raise no gradient instead of attribute dim not found ([autodiff] Raise no gradient instead of attribute dim not found #2542) (by Mingrui Zhang)
• [doc] Fix command typo in contributor guide ([doc] Fix format command in contributor guide #2545) (by Yi Xu)
• [bug] Fix python detection on windows ([bug] Fix python detection on windows #2528) (by Hoildkv)
• [Refactor] Use setup.py from root dir. ([Refactor] Use setup.py from root dir. #2540) (by Ailing)
• [test] [bug] Avoid accessing negative indices ([test] [bug] Avoid accessing negative indices #2538) (by Yi Xu)
• [lang] Add a name parameter to fields ([lang] Add a name parameter to fields #2534) (by ljss)
• [refactor] Move snode tree maintainance out of python ([refactor] Move snode tree maintainance out of python #2530) (by Jiasheng Zhang)
• [Example] Fix an oversight on the variance computation ([Example] Fix an oversight on the variance computation #2536) (by Bob Cao)
• [Example] Use Taichi instead of numpy to perform tonemapping & significantly lower CPU's work ([Example] Use Taichi instead of numpy to perform tonemapping & significantly lower CPU's work #2535) (by Bob Cao)
• [doc] fix outdated links of examples in README.md ([doc] Fix outdated links of examples in README.md #2533) (by Mingrui Zhang)
• [doc] Update links in the readme file. ([doc] Update links in the readme file. #2523) (by Chengchen(Rex) Wang)
• [windows] Use %lld as 64-bit integer output format on Windows ([windows] Use %lld as 64-bit integer output format on Windows #2525) (by xumingkuan)
• [bug] Set use_unified_memory=True for tests with pointer fields with 32-bit data types ([bug] Set use_unified_memory=True for tests with pointer fields with 32-bit data types #2521) (by xumingkuan)
• [Refactor]Move llvm runtime build for archs to cmake from C++. ([Refactor] Move llvm runtime build for archs from C++ to cmake. #2524) (by Ailing)
• [Bug] Warp reduction bug fix ([Bug] Warp reduction bug fix #2519) (by Dunfan Lu)
• [misc] Output "taichi_cpp_tests.exe" to the "bin" folder on Windows ([misc] Output "taichi_cpp_tests.exe" to the "bin" folder on Windows #2515) (by xumingkuan)
• [misc] Import template and ext_arr and kernel in python code ([misc] Import template and ext_arr and kernel in python code #2514) (by ljcc0930)
• [wasm] Add wasm_set_kernel_parameter_* into runtime.cpp ([wasm] Add wasm_set_kernel_parameter_* into runtime.cpp #2510) (by squarefk)

[ljcc0930]

LGTM