update-common: add missing semicolon

Quoting this page[1] on the differences in sed implementations:

function lists (multiple function calls enclosed in {...}), be sure
to also terminate the last function, before the closing }, with ;.

We need to terminate every function in a function list with a newline (or semicolon).

[1]https://riptutorial.com/sed/topic/9436/bsd-macos-sed-vs--gnu-sed-vs--the-posix-sed-specification

See: vtk/vtk#17593 (closed)

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Cc: @ken-martin