only do coverage for one build, not all

Author: mohawk2

.travis.yml

@@ -9,7 +9,6 @@ language: perl
 perl:
   - "blead"
   - "dev"
-  - "5.28"
   - "5.26"
   - "5.24"
   - "5.22"
@@ -22,14 +21,16 @@ perl:
   - "5.8"
 env:
   global:
-    - COVERAGE="coveralls codecov"
     - DBICTEST_PG_DSN=dbi:Pg:dbname=sqlt_test
     - DBICTEST_PG_USER=postgres
     - SPLIT_BUILD=0
 matrix:
   allow_failures:
     - perl: "blead"
     - perl: "dev"
+  include:
+    - perl: "5.28"
+      env: COVERAGE="coveralls codecov"
 before_install:
   - eval $(curl https://travis-perl.github.io/init) --perl
   - cpan-install File::ShareDir::Install # absolute minimum for Makefile.PL