Fix upload_to_sonatype script.

[copybara-service]

Fix upload_to_sonatype script.

See https://github.com/google/dagger/actions/runs/21184694321/job/60937879624.

This CL fixes a bug in the script that incorrectly filters the repositories based on state. In particular, the jq command for filtering should use == rather than =.

Before:

$ echo '{
  "repositories": [
    {
      "key": "XXX.XXX.XXX/com.google.dagger",
      "state": "closed"
    },
    {
      "key": "YYY.YYY.YYY/com.google.dagger",
      "state": "open"
    }
  ]
}' | jq '.repositories | map(select(.state = "open"))'


[
  {
    "key": "XXX.XXX.XXX/com.google.dagger",
    "state": "closed"
  },
  {
    "key": "YYY.YYY.YYY/com.google.dagger",
    "state": "open"
  }
]

After:

$ echo '{
  "repositories": [
    {
      "key": "XXX.XXX.XXX/com.google.dagger",
      "state": "closed"
    },
    {
      "key": "YYY.YYY.YYY/com.google.dagger",
      "state": "open"
    }
  ]
}' | jq '.repositories | map(select(.state = "open"))'

[
  {
    "key": "YYY.YYY.YYY/com.google.dagger",
    "state": "open"
  }
]

RELNOTES=N/A