Resolve min as the earliest compatible Julia version (compatible with the user's project) (#202)

* Support the special version "MIN"

* Support JULIA_PROJECT

* Add tests

* Add forgotten test fixtures

* Get latest prerelease/release

* No special pre-release behaviour

* Add test for NPM semver difference

* Robust test suite

* Disallow less-than-equal

* Refactor validJuliaCompatRange to return a validRange

* Rename MIN to min

* Rename getProjectFile to getProjectFilePath

* Comment on "project" input

* Additional tests for getProjectFilePath

* Add comment on `juliaCompatRange`

Co-authored-by: Dilum Aluthge <dilum@aluthge.com>

* Update dependencies

---------

Co-authored-by: Dilum Aluthge <dilum@aluthge.com>

README.md

@@ -71,6 +71,11 @@ This action sets up a Julia environment for use in actions by downloading a spec
     #
     # Default: false
     show-versioninfo: ''
+
+    # Set the path to the project directory or file to use when resolving some versions (e.g. `min`).
+    #
+    # Defaults to using JULIA_PROJECT if defined, otherwise '.'
+    project: ''
 ```
 
 ### Outputs
@@ -121,6 +126,7 @@ You can either specify specific Julia versions or version ranges. If you specify
 - `'pre'` will install the latest prerelease build (RCs, betas, and alphas).
 - `'nightly'` will install the latest nightly build.
 - `'1.7-nightly'` will install the latest nightly build for the upcoming 1.7 release. This version will only be available during certain phases of the Julia release cycle.
+- `'min'` will install the earliest supported version of Julia compatible with the project. Especially useful in monorepos.
 
 Internally the action uses node's semver package to resolve version ranges. Its [documentation](https://github.com/npm/node-semver#advanced-range-syntax) contains more details on the version range syntax. You can test what version will be selected for a given input in this JavaScript [REPL](https://repl.it/@SaschaMann/setup-julia-version-logic).