feat: support multiple plugins for the analyzeCommits step

In case multiple plugins with a `analyzeCommits` step are configured, all of them will be executed and the highest release type (`major` > `minor`, `patch`) will be used.

lib/definitions/plugins.js

@@ -6,28 +6,30 @@ const {RELEASE_TYPE, RELEASE_NOTES_SEPARATOR} = require('./constants');
 
 module.exports = {
   verifyConditions: {
-    multiple: true,
     required: false,
     pipelineConfig: () => ({settleAll: true}),
   },
   analyzeCommits: {
     default: ['@semantic-release/commit-analyzer'],
-    multiple: false,
     required: true,
     outputValidator: output => !output || RELEASE_TYPE.includes(output),
     preprocess: ({commits, ...inputs}) => ({
       ...inputs,
       commits: commits.filter(commit => !/\[skip\s+release\]|\[release\s+skip\]/i.test(commit.message)),
     }),
-    postprocess: ([result]) => result,
+    postprocess: results =>
+      RELEASE_TYPE[
+        results.reduce((highest, result) => {
+          const typeIndex = RELEASE_TYPE.indexOf(result);
+          return typeIndex > highest ? typeIndex : highest;
+        }, -1)
+      ],
   },
   verifyRelease: {
-    multiple: true,
     required: false,
     pipelineConfig: () => ({settleAll: true}),
   },
   generateNotes: {
-    multiple: true,
     required: false,
     outputValidator: output => !output || isString(output),
     pipelineConfig: () => ({
@@ -42,9 +44,8 @@ module.exports = {
     postprocess: (results, {env}) => hideSensitive(env)(results.filter(Boolean).join(RELEASE_NOTES_SEPARATOR)),
   },
   prepare: {
-    multiple: true,
     required: false,
-    pipelineConfig: ({generateNotes}, logger) => ({
+    pipelineConfig: ({generateNotes}) => ({
       getNextInput: async context => {
         const newGitHead = await gitHead({cwd: context.cwd});
         // If previous prepare plugin has created a commit (gitHead changed)
@@ -59,7 +60,6 @@ module.exports = {
     }),
   },
   publish: {
-    multiple: true,
     required: false,
     outputValidator: output => !output || isPlainObject(output),
     pipelineConfig: () => ({
@@ -72,13 +72,11 @@ module.exports = {
     }),
   },
   success: {
-    multiple: true,
     required: false,
     pipelineConfig: () => ({settleAll: true}),
     preprocess: ({releases, env, ...inputs}) => ({...inputs, env, releases: hideSensitiveValues(env, releases)}),
   },
   fail: {
-    multiple: true,
     required: false,
     pipelineConfig: () => ({settleAll: true}),
     preprocess: ({errors, env, ...inputs}) => ({...inputs, env, errors: hideSensitiveValues(env, errors)}),