Add Test::Pod test dependency

[paultcochrane]

After having built a pristine Perl with perlbrew it turned out that after having installed all the dependencies via cpanm --installdeps . that the Test::Pod module was still required in order to run dzil test. This patch adds Test::Pod to the list of test dependencies so that this issue doesn't happen to someone else.

If you need this PR changed in any way, please just let me know and I'll update it and resubmit.

[coveralls]

Coverage remained the same at 99.412% when pulling 913298ce529fabdd1ae12f96eb43da64da7c6bd0 on paultcochrane:pr/add-test-prereq into bdd91252732b952fdc14e3fda4d209696d5b52ed on fayland:master.

[coveralls]

Coverage remained the same at 99.412% when pulling 913298ce529fabdd1ae12f96eb43da64da7c6bd0 on paultcochrane:pr/add-test-prereq into bdd91252732b952fdc14e3fda4d209696d5b52ed on fayland:master.

[codecov-io]

Current coverage is 95.88% (diff: 100%)

Merging #19 into master will not change coverage

@@             master        #19   diff @@
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  Methods           0          0          
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  Branches         17         17          
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  Hits            163        163          
  Misses            1          1          
  Partials          6          6          

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[fayland]

thanks.