Fix #161: make sure IO::String dep is present

Makefile

@@ -29,7 +29,7 @@ prereq-debs:
 	apt-get install -y sqlite3 libsqlite3-dev libdbd-sqlite3-perl cpanminus starman libxml2 curl                         \
 	    libtext-xslate-perl libplack-perl libconfig-tiny-perl libdatetime-format-http-perl libjson-maybexs-perl          \
 	    libuuid-tiny-perl libcapture-tiny-perl libconfig-simple-perl libdbi-perl libfile-slurper-perl libfile-touch-perl \
-	    libfile-copy-recursive-perl libxml-rss-perl libmodule-install-perl                                               \
+	    libfile-copy-recursive-perl libxml-rss-perl libmodule-install-perl libio-string-perl                             \
 	    libmoose-perl libmoosex-types-datetime-perl libxml-libxml-perl
 
 .PHONY: prereq-perl

Makefile.PL

@@ -32,6 +32,7 @@ WriteMakefile(
     'File::Touch'            => '0',
     'HTML::SocialMeta'       => '0',
     'HTTP::Body'             => '0',
+    'IO::String'             => '0',
     'JSON::MaybeXS'          => '0',
     'List::Util'             => '0',
     'Mojo::File'             => '0',