Add support for json in postgres query

**Describe the bug**
Inspektor doesn't support json query support. 

**To Reproduce**
Parse the following query 
```
select * from tmpdb where cast(meta1->'refferedBy' as text) = '3332'
```
you'll get the following error
```
ParserError("Expected an expression:, found: >")
```

**Expected behavior**
Inspektor should be able to parse json query 