Check exact version match

src/setup-elixir.js

@@ -67,8 +67,12 @@ async function getElixirVersion(spec, otpVersion) {
 }
 
 function getVersionFromSpec(spec, versions) {
+  if (versions.includes(spec)) {
+    return spec;
+  } else {
     const range = semver.validRange(spec)
     return semver.maxSatisfying(versions, range)
+  }
 }
 
 async function getOtpVersions() {