fix: make properties required in interface

---
type: pre_commit_static_analysis_report
description: Results of running static analysis checks when committing changes.
report:
  - task: lint_filenames
    status: passed
  - task: lint_editorconfig
    status: passed
  - task: lint_markdown
    status: na
  - task: lint_package_json
    status: na
  - task: lint_repl_help
    status: na
  - task: lint_javascript_src
    status: na
  - task: lint_javascript_cli
    status: na
  - task: lint_javascript_examples
    status: na
  - task: lint_javascript_tests
    status: na
  - task: lint_javascript_benchmarks
    status: na
  - task: lint_python
    status: na
  - task: lint_r
    status: na
  - task: lint_c_src
    status: na
  - task: lint_c_examples
    status: na
  - task: lint_c_benchmarks
    status: na
  - task: lint_c_tests_fixtures
    status: na
  - task: lint_shell
    status: na
  - task: lint_typescript_declarations
    status: passed
  - task: lint_typescript_tests
    status: na
  - task: lint_license_headers
    status: passed
---

Author: gururaj1512

lib/node_modules/@stdlib/stats/base/ztest/two-sample/results/float32/docs/types/index.d.ts

@@ -125,12 +125,12 @@ declare class ResultsStruct {
 	/**
 	* Sample mean of `x`.
 	*/
-	xmean?: number;
+	xmean: number;
 
 	/**
 	* Sample mean of `y`.
 	*/
-	ymean?: number;
+	ymean: number;
 
 	/**
 	* Test method.