fix(.nvmrc)

closes #1051

fixtures/.nvmrc

@@ -0,0 +1 @@
+^20.0.0

src/utils/devenv.test.ts

@@ -80,6 +80,7 @@ Deno.test("devenv.ts", async runner => {
           '[email protected]',
         ],
         [".node-version", "[email protected]"],
+        [".nvmrc", "nodejs.org^20"],
         ["python-version/std/.python-version", "python.org~3.10"],
         ["python-version/commented/.python-version", "python.org~3.11"],
         [".ruby-version", "[email protected]"],

src/utils/devenv.ts

@@ -145,7 +145,8 @@ export default async function(dir: Path) {
   async function version_file(path: Path, project: string) {
     let s = (await path.read()).trim()
     if (s.startsWith('v')) s = s.slice(1)  // v prefix has no effect but is allowed
-    s = `${project}@${s}`
+    if (isNumber(s.slice(0, 1))) s = `@${s}`  // bare numbers are single versions
+    s = `${project}${s}`
     pkgs.push(utils.pkg.parse(s))
   }