refactor: increase type specificity

---
type: pre_commit_static_analysis_report
description: Results of running static analysis checks when committing changes.
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---

Author: kgryte

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

@@ -18,6 +18,11 @@
 
 // TypeScript Version: 4.1
 
+/**
+* Alternative hypothesis.
+*/
+type Alternative = 'two-sided' | 'greater' | 'less';
+
 /**
 * Interface describing test results.
 */
@@ -30,7 +35,7 @@ interface Results {
 	/**
 	* Alternative hypothesis.
 	*/
-	alternative?: string;
+	alternative?: Alternative;
 
 	/**
 	* Significance level.
@@ -85,7 +90,7 @@ declare class ResultsStruct {
 	/**
 	* Alternative hypothesis.
 	*/
-	alternative: string;
+	alternative: Alternative;
 
 	/**
 	* Significance level.

lib/node_modules/@stdlib/stats/base/ztest/one-sample/results/float64/docs/types/index.d.ts

@@ -18,6 +18,11 @@
 
 // TypeScript Version: 4.1
 
+/**
+* Alternative hypothesis.
+*/
+type Alternative = 'two-sided' | 'greater' | 'less';
+
 /**
 * Interface describing test results.
 */
@@ -30,7 +35,7 @@ interface Results {
 	/**
 	* Alternative hypothesis.
 	*/
-	alternative?: string;
+	alternative?: Alternative;
 
 	/**
 	* Significance level.
@@ -85,7 +90,7 @@ declare class ResultsStruct {
 	/**
 	* Alternative hypothesis.
 	*/
-	alternative: string;
+	alternative: Alternative;
 
 	/**
 	* Significance level.