glslc --version always shows v2023.8 even in newer version.

We found that glslc --version always shows v2023.8 even in newer version.

For example, in v2025.1:
$ glslc --version
shaderc v2023.8 v2025.1
spirv-tools 2025.1.1
glslang 15.2.0

The runtime version of glslc is generated by utils/update_build_version.py. In the deduce_software_version() function, it matches the first well-formed version-and-date line in the CHANGES file. However, in the CHANGES file, all version number lines after v2023.8 are missing the date section, which causes the v2023.8 version to always be matched even in newer versions.