fix: typescript 2309 error

[ryu-sato]

This PR fix TS2309 Error.

node ➜ /workspaces/tmp_human-format (master) $ pnpm exec tsc
node_modules/.pnpm/human-format@1.2.1/node_modules/human-format/index.d.ts:111:3 - error TS2309: An export assignment cannot be used in a module with other exported elements.

111   export = humanFormat;
      ~~~~~~~~~~~~~~~~~~~~~


Found 1 error in node_modules/.pnpm/human-format@1.2.1/node_modules/human-format/index.d.ts:111

Environments:

node ➜ /workspaces/tmp_human-format (master) $ pnpm exec tsc --version
Version 5.9.3
node ➜ /workspaces/tmp_human-format (master) $ pnpm exec tsc --showConfig
{
    "compilerOptions": {
        "module": "nodenext",
        "target": "esnext",
        "types": [],
        "sourceMap": true,
        "declaration": true,
        "declarationMap": true,
        "noUncheckedIndexedAccess": true,
        "exactOptionalPropertyTypes": true,
        "strict": true,
        "jsx": "react-jsx",
        "verbatimModuleSyntax": false,
        "isolatedModules": true,
        "noUncheckedSideEffectImports": true,
        "moduleDetection": "force",
        "skipLibCheck": false,
        "moduleResolution": "nodenext",
        "esModuleInterop": true,
        "allowSyntheticDefaultImports": true,
        "resolvePackageJsonExports": true,
        "resolvePackageJsonImports": true,
        "resolveJsonModule": true,
        "preserveConstEnums": true,
        "useDefineForClassFields": true,
        "noImplicitAny": true,
        "noImplicitThis": true,
        "strictNullChecks": true,
        "strictFunctionTypes": true,
        "strictBindCallApply": true,
        "strictPropertyInitialization": true,
        "strictBuiltinIteratorReturn": true,
        "alwaysStrict": true,
        "useUnknownInCatchVariables": true
    },
    "files": [
        "./src/index.ts"
    ]
}