fix: remove duplicate addPath in setOutputs that shadowed pnpm.exe

setOutputs called addPath(node_modules/.bin) AFTER installPnpm had
already added the correct path (@pnpm/exe on Windows). Since
GITHUB_PATH entries are prepended, .bin ended up first in PATH,
causing PowerShell to find npm's broken shims instead of pnpm.exe.

Author: zkochan