chore: bump rust toolchain version to 1.84

[zong-zhe]

1. Does this PR affect any open issues?(Y/N) and add issue references (e.g. "fix #123", "re #123".):

• N
• Y

2. What is the scope of this PR (e.g. component or file name):

3. Provide a description of the PR(e.g. more details, effects, motivations or doc link):

• Affects user behaviors
• Contains syntax changes
• Contains variable changes
• Contains experimental features
• Performance regression: Consumes more CPU
• Performance regression: Consumes more Memory
• Other

4. Are there any breaking changes?(Y/N) and describe the breaking changes(e.g. more details, motivations or doc link):

• N
• Y

5. Are there test cases for these changes?(Y/N) select and add more details, references or doc links:

• Unit test
• Integration test
• Benchmark (add benchmark stats below)
• Manual test (add detailed scripts or steps below)
• Other

[coveralls]

Pull Request Test Coverage Report for Build 12866561838

Details

• 33 of 393 (8.4%) changed or added relevant lines in 25 files are covered.
• 126 unchanged lines in 20 files lost coverage.
• Overall coverage decreased (-0.3%) to 70.26%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
kclvm/api/src/lib.rs	0	1	0.0%
kclvm/runner/src/runner.rs	1	2	50.0%
kclvm/runtime/src/collection/mod.rs	0	1	0.0%
kclvm/runtime/src/panic/mod.rs	0	1	0.0%
kclvm/runtime/src/stdlib/assert_api.rs	0	1	0.0%
kclvm/runtime/src/base64/mod.rs	0	2	0.0%
kclvm/runtime/src/template/mod.rs	0	2	0.0%
kclvm/runtime/src/_kcl_run.rs	0	3	0.0%
kclvm/runtime/src/json/mod.rs	1	4	25.0%
kclvm/runtime/src/stdlib/plugin.rs	1	4	25.0%

Files with Coverage Reduction	New Missed Lines	%
kclvm/sema/src/advanced_resolver/node.rs	1	84.97%
kclvm/third-party/prost-wkt/wkt-types/src/pbany.rs	1	55.33%
kclvm/tools/src/LSP/src/tests.rs	1	95.0%
kclvm/ast/src/ast.rs	1	69.46%
kclvm/third-party/prost-wkt/wkt-types/src/pbtime.rs	1	83.78%
kclvm/runtime/src/regex/mod.rs	1	10.42%
kclvm/evaluator/src/proxy.rs	2	70.8%
kclvm/third-party/serde_yaml/src/mapping.rs	2	29.03%
kclvm/driver/src/lib.rs	2	79.49%
kclvm/third-party/serde_yaml/src/value/de.rs	2	79.06%

Totals
Change from base Build 12770073543:	-0.3%
Covered Lines:	52408
Relevant Lines:	74591

---

💛 - Coveralls