[db_migrator] Fix the broken version chain (#3014)

Signed-off-by: Vivek Reddy Karri <vkarri@nvidia.com>

Why I did
Warm Reboot from 202205 -> latest labels is failing because of an extra version that was added to 202205 and that was missing in later branches.

How I did it
Add a placeholder for version 3_0_7 in latest labels

How to verify it
WR from 202205 to 202305 and try running db_migrator

scripts/db_migrator.py

@@ -971,10 +971,19 @@ def version_3_0_5(self):
     def version_3_0_6(self):
         """
         Version 3_0_6
-        This is the latest version for 202211 branch
         """
 
         log.log_info('Handling version_3_0_6')
+        self.set_version('version_3_0_7')
+        return 'version_3_0_7'
+
+    def version_3_0_7(self):
+        """
+        Version 3_0_7
+        This is the latest version for 202205 branch
+        """
+
+        log.log_info('Handling version_3_0_7')
         self.set_version('version_4_0_0')
         return 'version_4_0_0'