fix: changed exports to '.' in package.json

[JinIgarashi]

Since I tried to upgrade vitest from 0.33.0 to 0.34.0 or above, vitest gives the following error.

Error: Failed to resolve entry for package "svelte-file-dropzone". The package may have incorrect main/module/exports specified in its package.json: Missing "." specifier in "svelte-file-dropzone" package
 ❯ packageEntryFailure ../../node_modules/vite/dist/node/chunks/dep-df561101.js:28691:11
 ❯ resolvePackageEntry ../../node_modules/vite/dist/node/chunks/dep-df561101.js:28686:9
 ❯ tryNodeResolve ../../node_modules/vite/dist/node/chunks/dep-df561101.js:28419:20
 ❯ Context.resolveId ../../node_modules/vite/dist/node/chunks/dep-df561101.js:28180:28
 ❯ Object.resolveId ../../node_modules/vite/dist/node/chunks/dep-df561101.js:44207:64
 ❯ async file:/Users/j_igarashi/Documents/git/UNDP-Data/geohub/node_modules/vite/dist/node/chunks/dep-df561101.js:65837:21
 ❯ async file:/Users/j_igarashi/Documents/git/UNDP-Data/geohub/node_modules/vite/dist/node/chunks/dep-df561101.js:44852:20
 ❯ addManuallyIncludedOptimizeDeps ../../node_modules/vite/dist/node/chunks/dep-df561101.js:46034:31
 ❯ optimizeServerSsrDeps ../../node_modules/vite/dist/node/chunks/dep-df561101.js:45638:5
 ❯ createDevSsrDepsOptimizer ../../node_modules/vite/dist/node/chunks/dep-df561101.js:45556:22

Looks like exports property in package.json must have .. I just changed it to ..

For your reference, the following package.json is the template generated by the latest sveltekit. It may need svelte property and types property as well, but I believe this PR's change is enough to pass vitest 0.34.0.

Default package.json by sveltekit template

```json { "name": "test", "version": "0.0.1", "scripts": { "dev": "vite dev", "build": "vite build && npm run package", "preview": "vite preview", "package": "svelte-kit sync && svelte-package && publint", "prepublishOnly": "npm run package", "test": "npm run test:integration && npm run test:unit", "check": "svelte-kit sync && svelte-check --tsconfig ./tsconfig.json", "check:watch": "svelte-kit sync && svelte-check --tsconfig ./tsconfig.json --watch", "lint": "prettier --plugin-search-dir . --check . && eslint .", "format": "prettier --plugin-search-dir . --write .", "test:integration": "playwright test", "test:unit": "vitest" }, "exports": { ".": { "types": "./dist/index.d.ts", "svelte": "./dist/index.js" } }, "files": [ "dist", "!dist/**/*.test.*", "!dist/**/*.spec.*" ], "peerDependencies": { "svelte": "^4.0.0" }, "devDependencies": { "@playwright/test": "^1.28.1", "@sveltejs/adapter-auto": "^2.0.0", "@sveltejs/kit": "^1.20.4", "@sveltejs/package": "^2.0.0", "@typescript-eslint/eslint-plugin": "^5.45.0", "@typescript-eslint/parser": "^5.45.0", "eslint": "^8.28.0", "eslint-config-prettier": "^8.5.0", "eslint-plugin-svelte": "^2.30.0", "prettier": "^2.8.0", "prettier-plugin-svelte": "^2.10.1", "publint": "^0.1.9", "svelte": "^4.0.5", "svelte-check": "^3.4.3", "tslib": "^2.4.1", "typescript": "^5.0.0", "vite": "^4.4.2", "vitest": "^0.32.2" }, "svelte": "./dist/index.js", "types": "./dist/index.d.ts", "type": "module" } ```