Correct Arduino CLI name in pull request template

Co-authored-by: per1234 <[email protected]>

Author: Roberto Sora

.github/PULL_REQUEST_TEMPLATE.md

@@ -19,7 +19,7 @@
 - **Does this PR introduce a breaking change, and is
 [titled accordingly](https://arduino.github.io/arduino-cli/latest/CONTRIBUTING/#breaking)?**
 <!-- If this PR is merged, will any users need to change their code, command-line invocations, build scripts or data files
-when upgrading from an older version of arduino-cli? -->
+when upgrading from an older version of Arduino CLI? -->
 
 * **Other information**:
 <!-- Any additional information that could help the review process -->