chore: echo proxy should not accept multiple requests

[EkelmansPh]

If the previous request has not been granted yet, any incoming requests are not allowed.

TBD:

• Add unit tests for EchoProxy

[github-actions]

Dependency Review

✅ No vulnerabilities or license issues or OpenSSF Scorecard issues found.

Scanned Files

None

[github-actions]

🦙 MegaLinter status: ⚠️ WARNING

Descriptor	Linter	Files	Fixed	Errors	Warnings	Elapsed time
✅ ACTION	actionlint	12		0	0	0.26s
✅ CPP	clang-format	1028	8	0	0	6.82s
✅ DOCKERFILE	hadolint	2		0	0	0.38s
✅ JSON	jsonlint	7		0	0	0.16s
✅ JSON	prettier	7	0	0	0	0.58s
⚠️ MARKDOWN	markdownlint	6	0	4	0	1.18s
⚠️ MARKDOWN	markdown-link-check	6		1	0	115.85s
✅ MARKDOWN	markdown-table-formatter	6	0	0	0	0.23s
✅ REPOSITORY	checkov	yes		no	no	20.83s
✅ REPOSITORY	git_diff	yes		no	no	0.06s
✅ REPOSITORY	grype	yes		no	no	26.52s
✅ REPOSITORY	ls-lint	yes		no	no	0.06s
✅ REPOSITORY	secretlint	yes		no	no	6.03s
✅ REPOSITORY	syft	yes		no	no	2.07s
✅ REPOSITORY	trivy	yes		no	no	7.04s
✅ REPOSITORY	trivy-sbom	yes		no	no	0.17s
✅ REPOSITORY	trufflehog	yes		no	no	4.24s
⚠️ SPELL	lychee	138		59	0	10.5s
⚠️ YAML	prettier	22	1	1	0	0.85s
✅ YAML	v8r	22		0	0	5.35s
✅ YAML	yamllint	22		0	0	0.54s

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