revert: update dependency conventional-changelog-conventionalcommits …

…to v8 (#11)

Reverts #10 because it breaks the
release step.

```
RangeError: Invalid time value
    at committerDate (/home/runner/work/fluent-bit-multiline/fluent-bit-multiline/.release/node_modules/conventional-changelog-writer/index.js:80:30)
    at /home/runner/work/fluent-bit-multiline/fluent-bit-multiline/.release/node_modules/conventional-changelog-writer/lib/util.js:202:17
    at Array.forEach (<anonymous>)
    at processCommit (/home/runner/work/fluent-bit-multiline/fluent-bit-multiline/.release/node_modules/conventional-changelog-writer/lib/util.js:198:31)
    at /home/runner/work/fluent-bit-multiline/fluent-bit-multiline/.release/node_modules/conventional-changelog-writer/index.js:123:32 {
  pluginName: '@semantic-release/release-notes-generator'
```

.release/package.json

@@ -26,7 +26,7 @@
     "@semantic-release/git": "^10.0.1",
     "@semantic-release/github": "^10.0.0",
     "@semantic-release/release-notes-generator": "^13.0.0",
-    "conventional-changelog-conventionalcommits": "^8.0.0",
+    "conventional-changelog-conventionalcommits": "^7.0.2",
     "semantic-release": "^23.0.0"
   },
   "devDependencies": {