Update CHANGELOG for 21.4b1 release (#2151)

* Update CHANGELOG for 21.4b1 release

* Add pathspec minimum bump + update primer not to expect changes for virtualenv

Author: cooperlees

Diff for: CHANGES.md

@@ -1,6 +1,6 @@
 ## Change Log
 
-### Unreleased
+### 21.4b1
 
 #### _Black_
 
@@ -15,6 +15,10 @@
 - Don't remove necessary parentheses from assignment expression containing assert /
   return statements. (#2143)
 
+#### _Packaging_
+
+- Bump pathspec to >= 0.8.1 to solve invalid .gitignore exclusion handling
+
 ### 21.4b0
 
 #### _Black_

Diff for: src/black_primer/primer.json

@@ -112,7 +112,7 @@
     },
     "virtualenv": {
       "cli_arguments": [],
-      "expect_formatting_changes": true,
+      "expect_formatting_changes": false,
       "git_clone_url": "https://github.com/pypa/virtualenv.git",
       "long_checkout": false,
       "py_versions": ["all"]