fix: fix fmt toml. Only allow table after table in root scope

[He1pa]

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

• N
• Y fix kcl run --format toml returns wrong data kcl#1792

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 12632106511

Details

• 12 of 13 (92.31%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.1%) to 36.455%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
pkg/3rdparty/toml/encode.go	12	13	92.31%

Totals
Change from base Build 12631701775:	0.1%
Covered Lines:	5470
Relevant Lines:	15005

---

💛 - Coveralls

[zong-zhe]

LGTM