Merge torrust#835: chore(deps): update dependencies and improve robustness

103d55f chore(deps): update which next major version from (v6) to (v8) (Cameron Garnham)
19a96c6 chore(deps): update jsonwebtoken next major version (v10) (Cameron Garnham)
e7811f2 chore(deps): update derive_more next major version (v2) (Cameron Garnham)
519fbad chore(deps): update thiserror next major version (v2) (Cameron Garnham)
c400936 chore(deps): update toml next major version (v1) (Cameron Garnham)
68be605 chore: update dependencies (Cameron Garnham)
b13bf98 fix: embed verify-email template as compiled-in default (Cameron Garnham)

Pull request description:

  ## Summary
  Update multiple Rust dependencies to their latest versions, including several
  major version bumps, and implement two robustness improvements:
  - Embed verify-email template as compile-time default with file override
  - Isolate configuration test from environment using figment::Jail

  ## Dependency Updates
  ### Major Version Bumps
  - **derive_more**: v1 → v2 (with convert_case dependency)
  - **jsonwebtoken**: v9 → v10 (adds rust_crypto feature, replaces ring with pure-Rust crypto)
  - **thiserror**: v1 → v2 (in main crate and located-error package)
  - **toml**: v0 → v1 (toml 1.0 spec compliance)
  - **which**: v6 → v8 (simplified dependencies, drops winsafe)

  ### Significant Updates
  - **clap**: 4.5 → 4.6 (anstream 1.0, anstyle-parse 1.0)
  - **tokio**: 1.49 → 1.50
  - **chrono**: 0.4.43 → 0.4.44
  - **uuid**: 1.21 → 1.22
  - **aws-lc-rs**: 1.15 → 1.16 (aws-lc-sys 0.37 → 0.38)
  - **rustls**: 0.23.36 → 0.23.37
  - **serde_with**: 3.16 → 3.18
  - **tracing-subscriber**: 0.3.22 → 0.3.23
  - **wasm-bindgen** family: 0.2.108 → 0.2.114
  - **tempfile**: 3.25 → 3.27
  - **many other** transitive dependency updates

  ## Functional Improvements
  ### Verify-Email Template Embedding
  - Added `VERIFY_EMAIL_DEFAULT` constant with `include_str!` for compile-time embedding
  - Template loading now attempts `templates/verify.html` from working directory first
  - Falls back to embedded default if file is absent
  - Uses `add_raw_template` instead of `add_template_file` for consistency

  ### Configuration Test Isolation
  - Replaced `drop(initialize_configuration())` with `figment::Jail::expect_with`
  - Test now loads default config from `share/default/config/index.development.sqlite3.toml`
  - Sets `TORRUST_INDEX_CONFIG_TOML` environment variable within jail
  - Eliminates dependency on external environment variables during test execution
  - Added `#[allow(clippy::result_large_err)]` to suppress false positive lint

  ## Motivation
  - **Security**: Keep dependencies current with security patches
  - **Maintenance**: Reduce technical debt by updating major versions
  - **Robustness**: Ensure email verification works even when template file is missing
  - **Test Reliability**: Make configuration test deterministic and environment-independent
  - **Modernization**: Leverage latest features and performance improvements

  ## Testing Performed
  - `cargo check --workspace --all-targets --all-features` passes
  - `cargo test --workspace` passes (including updated config test)
  - Verified email template fallback behavior with missing file
  - Confirmed jsonwebtoken v10 with rust_crypto feature works correctly

  ## Breaking Changes
  None. All updates maintain backward compatibility:
  - `jsonwebtoken` v10 maintains same API with pure-Rust crypto backend
  - `derive_more` v2 preserves existing derive macros
  - `thiserror` v2 is source-compatible with v1
  - `toml` v1 maintains spec 1.0 compatibility
  - Template fallback ensures existing deployments continue working

  ## Migration Needed
  - No action required for existing users
  - Deployers can optionally place `templates/verify.html` to customize email template
  - Developers should run `cargo update` to sync local lockfile

  ## References
  - jsonwebtoken v10 changelog: https://github.com/Keats/jsonwebtoken/blob/master/CHANGELOG.md
  - thiserror v2 migration guide: https://github.com/dtolnay/thiserror/releases
  - toml v1.0 specification: https://toml.io/en/v1.0.0
  - figment Jail documentation: https://docs.rs/figment/latest/figment/struct.Jail.html

ACKs for top commit:
  da2ce7:
    ACK 103d55f

Tree-SHA512: 660d50f20cb88c852e095e43fb73bc5c3d7fb3f23cdc930cd11a19097e99047870a314c45c58b65d7b7121fc5c95fd34fa2818200eafcc13a03fd2e93b54b0ed

Author: da2ce7