Linear Regression example in README doesn't work

All the other examples work fine. The linear regression doesn't work.

```
julia> @mpi_do man copy!(A, Float32[2 1; 1 2])
ERROR: TaskFailedException:
On worker 4:
ArgumentError: arrays must have the same axes for copy! (consider using `copyto!`)
copy! at ./abstractarray.jl:719
top-level scope at none:1
eval at ./boot.jl:331 [inlined]
#7 at /Users/viral/.julia/packages/MPIClusterManagers/0ZYYQ/src/mpimanager.jl:510
#103 at /Users/viral/julia/usr/share/julia/stdlib/v1.5/Distributed/src/process_messages.jl:290
run_work_thunk at /Users/viral/julia/usr/share/julia/stdlib/v1.5/Distributed/src/process_messages.jl:79
run_work_thunk at /Users/viral/julia/usr/share/julia/stdlib/v1.5/Distributed/src/process_messages.jl:88
#96 at ./task.jl:356
Stacktrace:
[1] #remotecall_fetch#143 at /Users/viral/julia/usr/share/julia/stdlib/v1.5/Distributed/src/remotecall.jl:394 [inlined]
[2] remotecall_fetch(::Function, ::Distributed.Worker, ::Future) at /Users/viral/julia/usr/share/julia/stdlib/v1.5/Distributed/src/remotecall.jl:386
[3] remotecall_fetch(::Function, ::Int64, ::Future; kwargs::Base.Iterators.Pairs{Union{},Union{},Tuple{},NamedTuple{(),Tuple{}}}) at /Users/viral/julia/usr/share/julia/stdlib/v1.5/Distributed/src/remotecall.jl:421
[4] remotecall_fetch at /Users/viral/julia/usr/share/julia/stdlib/v1.5/Distributed/src/remotecall.jl:421 [inlined]
[5] macro expansion at /Users/viral/.julia/packages/MPIClusterManagers/0ZYYQ/src/mpimanager.jl:493 [inlined]
[6] (::MPIClusterManagers.var"#25#28"{Future})() at ./task.jl:356

...and 3 more exception(s).

Stacktrace:
[1] sync_end(::Channel{Any}) at ./task.jl:314
[2] macro expansion at ./task.jl:333 [inlined]
[3] mpi_do(::MPIManager, ::Function) at /Users/viral/.julia/packages/MPIClusterManagers/0ZYYQ/src/mpimanager.jl:490
[4] top-level scope at /Users/viral/.julia/packages/MPIClusterManagers/0ZYYQ/src/mpimanager.jl:511

julia> @mpi_do man copy!(B, Float32[4, 5])
ERROR: TaskFailedException:
On worker 4:
ArgumentError: arrays must have the same axes for copy! (consider using `copyto!`)
copy! at ./abstractarray.jl:719
top-level scope at none:1
eval at ./boot.jl:331 [inlined]
#9 at /Users/viral/.julia/packages/MPIClusterManagers/0ZYYQ/src/mpimanager.jl:510
#103 at /Users/viral/julia/usr/share/julia/stdlib/v1.5/Distributed/src/process_messages.jl:290
run_work_thunk at /Users/viral/julia/usr/share/julia/stdlib/v1.5/Distributed/src/process_messages.jl:79
run_work_thunk at /Users/viral/julia/usr/share/julia/stdlib/v1.5/Distributed/src/process_messages.jl:88
#96 at ./task.jl:356
Stacktrace:
[1] #remotecall_fetch#143 at /Users/viral/julia/usr/share/julia/stdlib/v1.5/Distributed/src/remotecall.jl:394 [inlined]
[2] remotecall_fetch(::Function, ::Distributed.Worker, ::Future) at /Users/viral/julia/usr/share/julia/stdlib/v1.5/Distributed/src/remotecall.jl:386
[3] remotecall_fetch(::Function, ::Int64, ::Future; kwargs::Base.Iterators.Pairs{Union{},Union{},Tuple{},NamedTuple{(),Tuple{}}}) at /Users/viral/julia/usr/share/julia/stdlib/v1.5/Distributed/src/remotecall.jl:421
[4] remotecall_fetch at /Users/viral/julia/usr/share/julia/stdlib/v1.5/Distributed/src/remotecall.jl:421 [inlined]
[5] macro expansion at /Users/viral/.julia/packages/MPIClusterManagers/0ZYYQ/src/mpimanager.jl:493 [inlined]
[6] (::MPIClusterManagers.var"#25#28"{Future})() at ./task.jl:356

...and 3 more exception(s).

Stacktrace:
[1] sync_end(::Channel{Any}) at ./task.jl:314
[2] macro expansion at ./task.jl:333 [inlined]
[3] mpi_do(::MPIManager, ::Function) at /Users/viral/.julia/packages/MPIClusterManagers/0ZYYQ/src/mpimanager.jl:490
[4] top-level scope at /Users/viral/.julia/packages/MPIClusterManagers/0ZYYQ/src/mpimanager.jl:511
```