fix test warnings

[juliasloan25]

A couple of our tests throw warnings about the deprecated reference_date, which comes from our call to ClimaUtilities.jl EveryCalendarDtSchedule in CheckpointCallback. We can replace reference_date with start_date. See tests throwing the errors here

Tests to fix

• bucket albedo types tests
• restart tests

┌ Warning: The keyword argument reference_date is deprecated. Use start_date instead.
│ caller = (ClimaLand.Bucket.PrescribedSurfaceAlbedo{Float32})(start_date::Dates.DateTime, space::ClimaCore.Spaces.SpectralElementSpace2D{ClimaCore.Grids.SpectralElementGrid2D{ClimaCore.Topologies.Topology2D{ClimaComms.SingletonCommsContext{ClimaComms.CPUSingleThreaded}, ClimaCore.Meshes.EquiangularCubedSphere{ClimaCore.Domains.SphereDomain{Float32}, ClimaCore.Meshes.NormalizedBilinearMap}, CartesianIndices{3, Tuple{Base.OneTo{Int64}, Base.OneTo{Int64}, Base.OneTo{Int64}}}, LinearIndices{3, Tuple{Base.OneTo{Int64}, Base.OneTo{Int64}, Base.OneTo{Int64}}}, Vector{Tuple{Int64, Int64, Int64, Int64, Bool}}, Vector{Tuple{Int64, Int64, Int64, Int64, Bool}}, Vector{Tuple{Int64, Int64}}, Vector{Int64}, Vector{Tuple{Bool, Int64, Int64}}, Vector{Int64}, Vector{Int64}, @NamedTuple{}, Vector{Tuple{Int64, Int64}}}, ClimaCore.Quadratures.GLL{3}, ClimaCore.Geometry.SphericalGlobalGeometry{Float32}, ClimaCore.DataLayouts.IJFH{ClimaCore.Geometry.LocalGeometry{(1, 2), ClimaCore.Geometry.LatLongPoint{Float32}, Float32, StaticArraysCore.SMatrix{2, 2, Float32, 4}}, 3, Array{Float32, 4}}, ClimaCore.DataLayouts.IJFH{Float32, 3, Array{Float32, 4}}, ClimaCore.DataLayouts.IFH{ClimaCore.Geometry.SurfaceGeometry{Float32, ClimaCore.Geometry.UVVector{Float32}}, 3, Array{Float32, 3}}, @NamedTuple{}}}; albedo_file_path::String, varname::String, regridder_type::Symbol) at Bucket.jl:181
└ @ ClimaLand.Bucket ~/work/ClimaLand.jl/ClimaLand.jl/src/standalone/Bucket/Bucket.jl:181