fix: Bump MSRV to 1.82.0

[devin-ai-integration]

chore: bump MSRV to 1.82.0

Summary

This PR updates the Minimum Supported Rust Version (MSRV) from various versions (1.74.1, 1.74.0, 1.81.0) to 1.82.0 across four LaunchDarkly Rust repositories as requested in SDK-1371.

Changes made:

• Updated rust-version fields in Cargo.toml files to 1.82.0
• Updated rustup override set commands in GitHub Actions workflows and tooling actions to use Rust 1.82
• Fixed a clippy lint issue in rust-server-sdk-redis that was exposed by the newer Rust version (manual_unwrap_or_default)

Repositories updated:

• rust-server-sdk-redis (1.74.1 → 1.82.0)
• rust-server-sdk-evaluation (1.74.0 → 1.82.0)
• rust-eventsource-client (1.81.0 → 1.82.0)
• rust-server-sdk (1.81.0 → 1.82.0)

Review & Testing Checklist for Human

⚠️ Risk Level: YELLOW - 3 items requiring attention

• Test the clippy fix behavior: Verify that the change from match result { Ok(r) => r, _ => false } to result.unwrap_or_default() in rust-server-sdk-redis/src/data_store.rs:249 doesn't change behavior in the Redis store's is_initialized method
• Verify MSRV consistency: Double-check that all MSRV references were updated consistently across all repositories and no old version references remain
• Test with Rust 1.82.0: Build and test the projects with the actual Rust 1.82.0 toolchain to ensure compatibility and that no new issues are introduced

Recommended test plan:

1. Install Rust 1.82.0 and test building all four repositories
2. Run the full test suites for each repository
3. For rust-server-sdk-redis specifically, test Redis integration functionality to ensure the clippy fix doesn't break initialization checks

---

Diagram

%%{ init : { "theme" : "default" }}%%
graph TD
    subgraph "rust-server-sdk-redis"
        A1["Cargo.toml<br/>rust-version: 1.74.1 → 1.82.0"]:::major-edit
        A2[".github/actions/tooling/action.yml<br/>rustup override: 1.74.1 → 1.82.0"]:::major-edit
        A3["src/data_store.rs<br/>clippy fix: match → unwrap_or_default"]:::major-edit
    end
    
    subgraph "rust-server-sdk-evaluation"
        B1["Cargo.toml<br/>rust-version: 1.74.0 → 1.82.0"]:::major-edit
        B2[".github/actions/tooling/action.yml<br/>rustup override: 1.74.0 → 1.82.0"]:::major-edit
    end
    
    subgraph "rust-eventsource-client"
        C1["eventsource-client/Cargo.toml<br/>rust-version: 1.81.0 → 1.82.0"]:::major-edit
        C2[".github/workflows/ci.yml<br/>rustup override: 1.81 → 1.82"]:::major-edit
    end
    
    subgraph "rust-server-sdk"
        D1["launchdarkly-server-sdk/Cargo.toml<br/>rust-version: 1.81.0 → 1.82.0"]:::major-edit
        D2["contract-tests/Cargo.toml<br/>rust-version: 1.81.0 → 1.82.0"]:::major-edit
        D3[".github/workflows/ci.yml<br/>rustup override: 1.81 → 1.82 (2 locations)"]:::major-edit
    end
    
    subgraph Legend
        L1[Major Edit]:::major-edit
        L2[Minor Edit]:::minor-edit
        L3[Context/No Edit]:::context
    end
    
    classDef major-edit fill:#90EE90
    classDef minor-edit fill:#87CEEB
    classDef context fill:#FFFFFF

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Notes

• Environment limitation: Local testing was not possible due to OpenSSL dependency issues in the development environment, so validation relied entirely on CI checks
• Breaking change: This MSRV bump is a breaking change for users on older Rust versions
• Clippy enforcement: The newer Rust version enforces stricter clippy rules, which required fixing the manual_unwrap_or_default lint in the Redis data store

Link to Devin run: https://app.devin.ai/sessions/61a6d2dcad704db2ae6197fcdbb2f68b
Requested by: @keelerm84

[devin-ai-integration]

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