Remove process.loadEnfFile() from main script (#112)

* Remove process.loadEnvFile from index.ts - Context in browserslist/browserslist#917
* Improve browserslist testing using Jasmine
* Set version to 2.9.3
* Docs updates to reflect the need for users to use `process.loadEnvFile()` if they are using .env files.

Author: tonypconway

README.md

@@ -31,7 +31,7 @@ If you are only using this module to generate minimum browser versions for Basel
 
 However, if you are targeting Newly available, using the [`getAllVersions()`](#get-data-for-all-browser-versions) function or heavily relying on the data for downstream browsers, you should update this module more frequently. If you target a feature cut off date within the last two months and your installed version of `baseline-browser-mapping` has data that is more than 2 months old, you will receive a console warning advising you to update to the latest version when you call `getCompatibleVersions()` or `getAllVersions()`.
 
-If you want to suppress these warnings you can use the `suppressWarnings: true` option in the configuration object passed to `getCompatibleVersions()` or `getAllVersions()`. Alternatively, you can use the `BASELINE_BROWSER_MAPPING_IGNORE_OLD_DATA=true` environment variable when running your build process. This module also respects the `BROWSERSLIST_IGNORE_OLD_DATA=true` environment variable. Environment variables can also be provided in a `.env` file from Node 20 onwards.
+If you want to suppress these warnings you can use the `suppressWarnings: true` option in the configuration object passed to `getCompatibleVersions()` or `getAllVersions()`. Alternatively, you can use the `BASELINE_BROWSER_MAPPING_IGNORE_OLD_DATA=true` environment variable when running your build process. This module also respects the `BROWSERSLIST_IGNORE_OLD_DATA=true` environment variable. Environment variables can also be provided in a `.env` file from Node 20 onwards; however, this module does not load .env files automatically to avoid conflicts with other libraries with different requirements.  You will need to use `process.loadEnvFile()` or a library like `dotenv` to load .env files before `baseline-browser-mapping` is called.
 
 If you want to ensure [reproducible builds](https://www.wikiwand.com/en/articles/Reproducible_builds), we strongly recommend using the `widelyAvailableOnDate` option to fix the Widely available date on a per build basis to ensure dependent tools provide the same output and you do not produce data staleness warnings. If you are using [`browserslist`](https://github.com/browserslist/browserslist) to target Baseline Widely available, consider automatically updating your `browserslist` configuration in `package.json` or `.browserslistrc` to `baseline widely available on {YYYY-MM-DD}` as part of your build process to ensure the same or sufficiently similar list of minimum browsers is reproduced for historical builds.