Flush stdout before subprocess.run

This commit adds sys.stdout.flush() before subprocess.run() in
ansible_collection.py. Without this, the print statements are shown
after the command output when building in mock.

ansible_collection.py

@@ -70,6 +70,9 @@ class AnsibleCollection:
         )
         print(f"Running: {args}")
         print()
+        # Without this, the print statements are shown after the command
+        # output when building in mock.
+        sys.stdout.flush()
         subprocess.run(args, check=True, cwd=self.collection_srcdir)
         print()
 
@@ -90,6 +93,9 @@ class AnsibleCollection:
             args = ("ansible-test", "units", *extra_args)
             print(f"Running: {args}")
             print()
+            # Without this, the print statements are shown after the command
+            # output when building in mock.
+            sys.stdout.flush()
             subprocess.run(args, cwd=temppath, check=True)