buildpdf GitHub action should support all correct specification states

[kbroch-rivosinc]

Specification states: https://wiki.riscv.org/display/HOME/Specification+States

Currently this: https://github.com/riscv/docs-spec-template/blob/main/.github/workflows/build-pdf.yml#L16

Prompted by this: riscv/riscv-zabha@ea4f0a1