Make pg_dump compatible with 13.3 db server

[akankshakumari393]

Change Overview

This PR updates the postgres-kanister-tools base image to postgres:13.3-alpine

Pull request type

Please check the type of change your PR introduces:

• 🚧 Work in Progress
• 🌈 Refactoring (no functional changes, no api changes)
• 🐹 Trivial/Minor
• 🐛 Bugfix
• 🌻 Feature
• 🗺️ Documentation
• 🤖 Test

Issues

• #XXX

Test Plan

• 💪 Manual
• ⚡ Unit test
• 💚 E2E

./build/integration-test.sh RDSPostgreSQLDump

https://gist.github.com/A-kanksh-a/d7d75a6718a15c63a265713006a483c0

[PrasadG193]

@A-kanksh-a could you please also verify if it doesn't break stable/postgress app?

[akankshakumari393]

Verified :
./build/integration-test.sh PostgreSQL

Running integration tests:
~/KASTEN/kanister/pkg/testing ~/KASTEN/kanister
=== RUN Test
OK: 1 passed
--- PASS: Test (61.77s)
PASS
ok github.com/kanisterio/kanister/pkg/testing 61.806s
~/KASTEN/kanister