(devel/R-testthat) Updated 3.1.6 to 3.1.8

# testthat 3.1.8

* `expect_snapshot()` differences no longer use quotes.

* `expect_error()`, `expect_warning()`, and `expect_message()` now correctly
  enforce that the condition is of the expected base class (e.g. error,
  warning, messsage) even when the `class` argument is used (#1168).

* `it()` now calls `local_test_context()` so that it behaves more
  similarly to `test_that()` (#1731), and is now exported so that you
  can more easily run BDD tests interactively (#1587)

* `skip_on_bioc()` now uses the documented environment variable
  (`IS_BIOC_BUILD_MACHINE`) (#1712).

* `source_file()`, which is used by various parts of the helper and
  setup/teardown machinery, now reports the file name in the case of
  errors (#1704).

* `test_path()` now works when called within helper files (#1562).

* New `vignette("special-files")` describes the various special files
  that testthat uses (#1638).

* `with_mocked_bindings()` and `local_mocked_bindings()` now also bind in the
  imports namespace and can mock S3 methods. These changes make them good
  substitutes for the deprecated functions `with_mock()` and `local_mock()`, so
  those older functions now recommend switching to the newer equivalents
  instead of using the mockr or mockery packages.

# testthat 3.1.7

* `expect_setequal()` gives more actionable feedback (#1657).

* `expect_snapshot()` no longer elides new lines when run interactively (#1726).

* Experimental new `with_mocked_bindings()` and `local_mocked_bindings()`
  (#1739).

(mef)