Bump mailer from 438.v02c7f0a_12fa_4 to 448.v5b_97805e3767 (#7620)

Bumps [mailer](https://github.com/jenkinsci/mailer-plugin) from 438.v02c7f0a_12fa_4 to 448.v5b_97805e3767.
- [Release notes](https://github.com/jenkinsci/mailer-plugin/releases)
- [Commits](https://github.com/jenkinsci/mailer-plugin/commits)

---
updated-dependencies:
- dependency-name: org.jenkins-ci.plugins:mailer
  dependency-type: direct:development
...
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Co-authored-by: Ndependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

test/pom.xml

@@ -176,7 +176,7 @@ THE SOFTWARE.
     <dependency>
       <groupId>org.jenkins-ci.plugins</groupId>
       <artifactId>mailer</artifactId>
-      <version>438.v02c7f0a_12fa_4</version>
+      <version>448.v5b_97805e3767</version>
       <scope>test</scope>
     </dependency>
     <dependency>