(gha) Fix acceptance.yaml openvox-release negation

Boolean values are tricky in github actions.
actions/runner#1483
! gtihub.event.inputs.pre-release-build always set openvox-released to
false, as though ! coerced pre-release-build to a string and then return
false since a string is truthy, perhaps.

Author: jpartlow

.github/workflows/acceptance.yaml

@@ -66,7 +66,7 @@ jobs:
           install-openvox: true
           openvox-version: ${{ github.event.inputs.version }}
           openvox-collection: ${{ github.event.inputs.collection }}
-          openvox-released: ${{ ! github.event.inputs.pre-release-build }}
+          openvox-released: ${{ github.event.inputs.pre-release-build == 'false' }}
           openvox-artifacts-url: ${{ github.event.inputs.artifacts-url }}
           vms: |-
             [