chore: Prepare release 1.3.0

[TheRealAgentK]

Prepares the 1.3.0 release.

Version bump

• pubspec.yaml: 1.2.1 → 1.3.0
• bin/raygun_cli.dart: 1.2.1 → 1.3.0

Changes since 1.2.1

• feat: Support config file for arguments like the app-id #5 add .env config file support (feat: #5 add .env config file support #62)
• chore(deps): bump build_runner from 2.11.1 to 2.13.1 (chore(deps): bump build_runner from 2.11.1 to 2.13.1 #56)
• chore(deps): bump test from 1.30.0 to 1.31.0 (chore(deps): bump test from 1.30.0 to 1.31.0 #57)
• chore(deps): bump mockito from 5.6.3 to 5.6.4 (chore(deps): bump mockito from 5.6.3 to 5.6.4 #58)
• chore(deps): bump build_runner from 2.13.1 to 2.15.0 (chore(deps): bump build_runner from 2.13.1 to 2.15.0 #59)
• chore(deps): bump test from 1.31.0 to 1.31.1 (chore(deps): bump test from 1.31.0 to 1.31.1 #60)
• chore(deps): bump mockito from 5.6.4 to 5.6.5 (chore(deps): bump mockito from 5.6.4 to 5.6.5 #61)

Minor bump because #62 introduces a new user-facing capability (.env config file discovery).

Release steps after merge

1. Create a GitHub Release tagged 1.3.0 targeting main.
2. The release.yml workflow will build and upload Linux, macOS, and Windows binaries automatically.

Verification

• dart format --set-exit-if-changed . — clean
• dart analyze — no issues
• dart test — 145/145 passed