Content block tokens supported in callbacks

Changes since langchain-core==1.4.3

hotfix(core): bump lockfile(s) (#38032) release(core): 1.4.4 (#38031) fix(core): support content block tokens in callbacks (#34739) chore(core): improve typing of Runnable __or__ (#34530) chore(core): fix some any generics (#34545) fix(core): accept sequence tool error content (#38005) fix(core): type structured tool error handler output (#38003) docs(core): document multimodal handling in get_buffer_string (#37994)