Add more labels to exempt-issue-labels in stale GitHub action

[seratch]

This pull request improves the stale GitHub Action job not to mark stale to issues with enhancement etc.

Category (place an x in each of the [ ])

• bolt (Bolt for Java)
• bolt-{sub modules} (Bolt for Java - optional modules)
• slack-api-client (Slack API Clients)
• slack-api-model (Slack API Data Models)
• slack-api-*-kotlin-extension (Kotlin Extensions for Slack API Clients)
• slack-app-backend (The primitive layer of Bolt for Java)

Requirements

Please read the Contributing guidelines and Code of Conduct before creating this issue or pull request. By submitting, you are agreeing to the those rules.

[codecov]

Codecov Report

Merging #899 (5f975a1) into main (bf21bb4) will decrease coverage by 0.01%.
The diff coverage is n/a.

@@             Coverage Diff              @@
##               main     #899      +/-   ##
============================================
- Coverage     77.16%   77.14%   -0.02%     
+ Complexity     3508     3507       -1     
============================================
  Files           386      386              
  Lines         10526    10526              
  Branches       1023     1023              
============================================
- Hits           8122     8120       -2     
- Misses         1806     1807       +1     
- Partials        598      599       +1     

Impacted Files	Coverage Δ
...imits/metrics/impl/BaseMemoryMetricsDatastore.java	88.66% <0.00%> (-1.34%)	⬇️

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[seratch]

slackapi/node-slack-sdk#1396 (comment)