Fix test snapshots

[Moohan]

There were some minor changes in the latest version of testthat https://testthat.r-lib.org/news/index.html#testthat-320 which changed how snapshots display warnings and errors.

There were also some changes in the latest version(s) of R - https://cran.r-project.org/doc/manuals/r-release/NEWS.html which were causing the (test-rename.R) snapshots to render differently on different versions.

[codecov]

Codecov Report

Merging #116 (28ef405) into master (a8cb369) will not change coverage.
The diff coverage is n/a.

❗ Current head 28ef405 differs from pull request most recent head 9895fcb. Consider uploading reports for the commit 9895fcb to get more accurate results

@@           Coverage Diff           @@
##           master     #116   +/-   ##
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  Coverage   97.30%   97.30%           
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  Files          13       13           
  Lines         408      408           
=======================================
  Hits          397      397           
  Misses         11       11           

[Moohan]

@Tina815 I think this is now resolved by 9895fcb It seems like it was just the release and devel versions which were failing, so I think that means it's down to something that has changed between R version 2.3 and 3.1 but I checked https://cran.r-project.org/doc/manuals/r-release/NEWS.html and couldn't see anything...