Bump checker-qual from 3.21.0 to 3.21.1 (#64)

Bumps [checker-qual](https://github.com/typetools/checker-framework) from 3.21.0 to 3.21.1.
- [Release notes](https://github.com/typetools/checker-framework/releases)
- [Changelog](https://github.com/typetools/checker-framework/blob/master/docs/CHANGELOG.md)
- [Commits](typetools/checker-framework@checker-framework-3.21.0...checker-framework-3.21.1)

---
updated-dependencies:
- dependency-name: org.checkerframework:checker-qual
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <[email protected]>

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

pom.xml

@@ -32,7 +32,7 @@
         <assertj-guava.version>3.4.0</assertj-guava.version>
         <byte-buddy.version>1.12.6</byte-buddy.version>
         <caffine.version>3.0.5</caffine.version>
-        <checker-qual.version>3.21.0</checker-qual.version>
+        <checker-qual.version>3.21.1</checker-qual.version>
         <classmate.version>1.5.1</classmate.version>
         <commons-configuration.version>1.10</commons-configuration.version>
         <commons-codec.version>1.15</commons-codec.version>