Add java 7 to build matrix
diff --git a/.github/workflows/build_cron.yml b/.github/workflows/build_cron.yml
index 210849d..5251e7f 100644
--- a/.github/workflows/build_cron.yml
+++ b/.github/workflows/build_cron.yml
@@ -12,7 +12,7 @@
     strategy:
       matrix:
         os: [ubuntu-latest, windows-latest, macos-latest]
-        java: [ 8 ]
+        java: [7, 8]
 
     steps:
     - uses: actions/checkout@v2