build: upgrade toolchain to 2025-06-30

[ibigbug]

🤔 This is a ...

• New feature
• Bug fix
• Performance optimization
• Enhancement feature
• Refactoring
• Code style optimization
• Test Case
• Branch merge
• Workflow
• Other (about what?)

🔗 Related issue link

💡 Background and solution

📝 Changelog

☑️ Self-Check before Merge

⚠️ Please check all items below before requesting a reviewing. ⚠️

• Doc is updated/provided or not needed
• Changelog is provided or not needed

[codecov]

Codecov Report

Attention: Patch coverage is 26.27346% with 275 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
clash-lib/src/app/dns/resolver/enhanced.rs	28.26%	32 Missing and 1 partial ⚠️
clash-lib/src/app/dns/dhcp.rs	0.00%	32 Missing ⚠️
clash-lib/src/session.rs	6.66%	14 Missing ⚠️
clash-lib/src/config/internal/convert/listener.rs	45.00%	9 Missing and 2 partials ⚠️
clash-lib/src/app/dns/config.rs	27.27%	8 Missing ⚠️
clash-lib/src/proxy/converters/shadowsocks.rs	0.00%	8 Missing ⚠️
clash-lib/src/proxy/mod.rs	0.00%	8 Missing ⚠️
...ontent_manager/providers/rule_provider/provider.rs	0.00%	7 Missing ⚠️
clash-lib/src/proxy/group/smart/mod.rs	0.00%	7 Missing ⚠️
clash-lib/src/proxy/transport/tls.rs	0.00%	6 Missing and 1 partial ⚠️
... and 66 more

📢 Thoughts on this report? Let us know!