Update proguard-rules.pro

[joashrajin]

fixed typo.

Description

Changes na to an in the comment

Fixes #3421

Testing Instructions

N/A

Checklist

• [na] If this is a user-facing change, I have added an entry in CHANGELOG.md
• [na ] Ensure the linter passes (./gradlew spotlessApply to automatically apply formatting/linting)
• [na] I have considered whether it makes sense to add tests for my changes
• [na] All strings that need to be localized are in modules/services/localization/src/main/res/values/strings.xml
• [na] Any jetpack compose components I added or changed are covered by compose previews
• [na] I have updated (or requested that someone edit) the spreadsheet to reflect any new or changed analytics.

I have tested any UI changes...

• with different themes
• with a landscape orientation
• with the device set to have a large display and font size
• for accessibility with TalkBack

[CLAassistant]

All committers have signed the CLA.

[wpmobilebot]

📲 You can test the changes from this Pull Request in 📱 Mobile by scanning the QR code below to install the corresponding build.

	App Name	📱 Mobile
	Build Type	debugProd
	Commit	05ad52a
	Direct Download	pocketcasts-app-prototype-build-pr3560-05ad52a.apk

📲 You can test the changes from this Pull Request in 🚗 Automotive by scanning the QR code below to install the corresponding build.

	App Name	🚗 Automotive
	Build Type	debugProd
	Commit	05ad52a
	Direct Download	pocketcasts-automotive-prototype-build-pr3560-05ad52a.apk

📲 You can test the changes from this Pull Request in ⌚ Wear by scanning the QR code below to install the corresponding build.

	App Name	⌚ Wear
	Build Type	debugProd
	Commit	05ad52a
	Direct Download	pocketcasts-wear-prototype-build-pr3560-05ad52a.apk