Update test matrix to 8.0

PiperOrigin-RevId: 574210079

.github/workflows/test_php_ext.yml

diff --git a/.github/workflows/test_php_ext.yml b/.github/workflows/test_php_ext.yml
index ec65715..e80afa0 100644
--- a/.github/workflows/test_php_ext.yml
+++ b/.github/workflows/test_php_ext.yml
@@ -41,7 +41,7 @@
     strategy:
       fail-fast: false   # Don't cancel all jobs if one fails.
       matrix:
-        version: ["7.4", "8.1", "8.2"]
+        version: ["8.0", "8.1", "8.2"]
     name: Build ${{ matrix.version }}
     runs-on: ubuntu-latest
     steps: