Fix PGP decryption for non-compressed messages

[chiranSachintha]

Purpose

Examples

Checklist

• Linked to an issue
• Updated the changelog
• Added tests
• Updated the spec
• Checked native-image compatibility

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[codecov]

Codecov Report

❌ Patch coverage is 83.33333% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 82.79%. Comparing base (f299f7d) to head (7c3ff3a).
⚠️ Report is 6 commits behind head on 2201.12.x.

Files with missing lines	Patch %	Lines
...allerina/stdlib/crypto/PgpDecryptionGenerator.java	83.33%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@               Coverage Diff               @@
##             2201.12.x     #619      +/-   ##
===============================================
- Coverage        83.57%   82.79%   -0.79%     
- Complexity         228      347     +119     
===============================================
  Files               30       42      +12     
  Lines             1291     1616     +325     
  Branches           181      254      +73     
===============================================
+ Hits              1079     1338     +259     
- Misses             168      187      +19     
- Partials            44       91      +47     

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