fix(VerifySignature): set Copyright to Frends, bump to 1.2.0

[Copilot]

Compliance rule requires <Copyright>Frends</Copyright> in all non-test .csproj files; Frends.Pgp.VerifySignature.csproj had Copyright (c) 2026 Frends EiPaaS instead.

Changes

• Frends.Pgp.VerifySignature.csproj: corrected <Copyright> value and bumped version 1.1.0 → 1.2.0
• CHANGELOG.md: added [1.2.0] entry

<!-- before -->
<Copyright>Copyright (c) 2026 Frends EiPaaS</Copyright>

<!-- after -->
<Copyright>Frends</Copyright>

[jefim]

@copilot fix the build errors

[Copilot]

@copilot fix the build errors

Fixed in the latest commit. NUnit 4 introduced an Assert.Throws<T>(Action) overload alongside the existing Assert.Throws<T>(TestDelegate), causing ambiguity when passing a plain lambda. The fix casts each lambda explicitly to Action to resolve the overload. Build now succeeds with 0 warnings and all 13 tests pass.