Fix unexpected `RecordNotFound` exception when pass a block to `ActiveFile::Base.find`

[yujideveloper]

Problem

I have occurred unexpected ActiveHash::RecordNotFound exception when pass a block to ActiveFile::Base.find.

Minimum reproduction code

class Country < ActiveYaml::Base
  set_filename "sample"
end

- id: 1
  name: US
- id: 2
  name: Canada
- id: 3
  name: Mexico

# Actual
Çountry.find { |c| c.name == "US" } # => ActiveHash::RecordNotFound

# Expected
Çountry.find { |c| c.name == "US" } # => <Country:0x000000010686c7f0 @attributes={:id=>1, :name=>"US"}>

This PR's changes

I fixed to pass a block to super method in ActiveFile::Base.find

[kbrock]

Could you add a spec for this?

[yujideveloper]

@kbrock I added specs. Could you review this?

[kbrock]

ran with test locally, all passed

[yujideveloper]

Thanks!