Add release freeze for 3.0.7 (databricks#1153)

## Description
- Checks in progress, freeze main till then.

## Testing
<!-- Describe how the changes have been tested-->

## Additional Notes to the Reviewer
NO_CHANGELOG=true

Author: samikshya-db

README.md

@@ -20,7 +20,7 @@ Add the following dependency to your `pom.xml`:
 <dependency>
   <groupId>com.databricks</groupId>
   <artifactId>databricks-jdbc</artifactId>
-  <version>3.0.6</version>
+  <version>3.0.7</version>
 </dependency>
 ```
 

development/.release-freeze.json

@@ -1,4 +1,4 @@
 {
-  "freeze": false,
-  "reason": ""
+  "freeze": true,
+  "reason": "3.0.7 release in progress"
 }