Fix stray end breaking parse of hybrid_systems.jl

[luke-kiernan]

src/hybrid_system_models/hybrid_systems.jl currently fails to parse on main, breaking precompilation of PowerOperationsModels.

The ReserveUp _emit_coverage_constraint! method has an extra end: the if/else already closes (line 1618) and the function closes (line 1621), leaving a stray end at line 1619.

        end      # closes `for`
    end          # closes `if/else`
    end          # ← stray, breaks parse
    return
end              # closes function

Introduced by the hybrid systems port (#104, merged via #105). Removing the stray end makes the file parse and the package precompile again.

🤖 Generated with Claude Code

[luke-kiernan]

Also addressed in #138 so I guess I'll close this