Github action ignores all environment variables defined in a bash.sh script

I have a bash script that sets a series of environment variables.

My action includes the following two steps:

  - name: Set env variables
    run: source ./setvars.sh

  - name: dump env variables
    run: env 

I notice setvars.sh runs successfully, but all of the variables defined inside it are missing after the steps.

How can I use a bash .sh script to add environment variables to the context of the workflow?