copilot: Add missing base and containers bounds. Refs #735.

[dancewithheart]

Adds missing dependency bounds to executable stanzas in copilot.cabal, as proposed in #735.

The bounds follow existing package conventions:

• base >= 4.9 && < 5
• containers >= 0.4 && < 0.9

Validated with:

cabal test all
cd copilot && cabal check
cabal v2-sdist copilot