Update min Gradle version for test matrix

Author: markushi

.github/workflows/test-matrix-agp-gradle.yaml

@@ -17,16 +17,16 @@ jobs:
       fail-fast: false
       matrix:
         agp: [ "7.2.1" ]
-        gradle: [ "7.4" ]
+        gradle: [ "7.6.4" ]
         java: [ "11" ]
         groovy: [ "1.2" ]
         include:
           - agp: "7.3.0"
-            gradle: "7.5"
+            gradle: "7.6.4"
             java: "11"
             groovy: "1.2"
           - agp: "7.4.0"
-            gradle: "7.6"
+            gradle: "7.6.4"
             java: "11"
             groovy: "1.2"
           - agp: "8.0.0"