Allow running npm version with arg --allow-same-version (#878)

docs/npm.md

@@ -94,6 +94,10 @@ basically defeats the purpose of 2FA (also, the OTP expires after a short period
 Use `npm.publishPath` to publish only a specific folder. For example, set `npm.publishPath` to `"dist"`. The default
 value is the current (root) folder (`"."`).
 
+## Allow same version
+
+Use `npm.allowSameVersion` to prevent throwing error when setting the new version to the same value as the current version.
+
 ## Monorepos
 
 Monorepos do not require extra configuration, but release-it handles only one package at a time. Also see how

lib/plugin/npm/npm.js

@@ -82,7 +82,8 @@ class npm extends Plugin {
 
     if (!this.config.isIncrement) return false;
 
-    const task = () => this.exec(`npm version ${version} --no-git-tag-version`);
+    const allowSameVersion = this.options.allowSameVersion || false;
+    const task = () => this.exec(['npm', 'version', version, '--no-git-tag-version', allowSameVersion ? '--allow-same-version' : undefined]);
     return this.spinner.show({ task, label: 'npm version' });
   }