chore: add unchecked Sendable conformance to AutoMockable

[nekrich]

When protocol conforms to Sendable, Xcode generates an error for the Mock class:

Non-final class 'SendableProtocolMock' cannot conform to 'Sendable'; use '@unchecked Sendable'

This PR fixes the issue.

UPD 1: Updated linux sources for template tests.
UPD 2: Prettify templates test failures. Show actual differences line by line. Not like git diff, but much easier to navigate on failures.

[nekrich]

@art-divin , little changes:

• Updated Linux sources for template tests.
• Prettify templates test failures. Show actual differences line by line. It's not like git diff, but it's much easier to navigate on failures. It provides info on missing and unexpected lines in expected file:

      Sourcery/Templates/Tests/TemplatesTests.swift:111: error: -[TemplatesTests.TemplatesTests AutoMockable_template__generates_expected_code] : failed - Missing line in AutoMockable.expected:1460:
  class SendableProtocolMock: SendableProtocol, @unchecked Sendable {
  
  Sourcery/Templates/Tests/TemplatesTests.swift:111: error: -[TemplatesTests.TemplatesTests AutoMockable_template__generates_expected_code] : failed - Missing line in AutoMockable.expected:1463:
      var value: Any {
  
  Sourcery/Templates/Tests/TemplatesTests.swift:111: error: -[TemplatesTests.TemplatesTests AutoMockable_template__generates_expected_code] : failed - Missing line in AutoMockable.expected:1464:
          get { return underlyingValue }
  
  Sourcery/Templates/Tests/TemplatesTests.swift:111: error: -[TemplatesTests.TemplatesTests AutoMockable_template__generates_expected_code] : failed - Missing line in AutoMockable.expected:1465:
          set(value) { underlyingValue = value }
  
  Sourcery/Templates/Tests/TemplatesTests.swift:111: error: -[TemplatesTests.TemplatesTests AutoMockable_template__generates_expected_code] : failed - Missing line in AutoMockable.expected:1466:
      }
  
  Templates/Tests/TemplatesTests.swift:111: error: -[TemplatesTests.TemplatesTests AutoMockable_template__generates_expected_code] : failed - Missing line to AutoMockable.expected:1467:
      var underlyingValue: (Any)!
  
  Sourcery/Templates/Tests/TemplatesTests.swift:111: error: -[TemplatesTests.TemplatesTests AutoMockable_template__generates_expected_code] : failed - Missing line in AutoMockable.expected:1471:
  }