sandwich-contexts: add bound on base · codedownio/sandwich@523d392

In the use of ‘head’

• Defaulting the type variable ‘a0’ to type ‘Integer’ in the following constraints

Failed to parse /home/runner/work/sandwich/sandwich/sandwich-contexts/test/Spec/NixContexts/PostgreSQL.hs: ParseFailed (SrcLoc "/home/runner/work/sandwich/sandwich/sandwich-contexts/test/Spec/NixContexts/PostgreSQL.hs" 7 1) "Parse error: import"