M4RA damage buff (#4233)

# About the pull request

Yup. It's a damage buff. Damage multiplier up 10%

# Explain why it's good for the game

The firerate slowdown has hit the M4RA particularly hard.

# Testing Photographs and Procedure
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<summary>Screenshots & Videos</summary>

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screenshots and the `<details>` tags.

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# Changelog

:cl: Morrow
balance: M4RA damage buffed by 10%
/:cl:

code/modules/projectiles/guns/rifles.dm

@@ -1542,7 +1542,7 @@
 	set_burst_amount(0)
 	accuracy_mult = BASE_ACCURACY_MULT + HIT_ACCURACY_MULT_TIER_5
 	accuracy_mult_unwielded = BASE_ACCURACY_MULT - HIT_ACCURACY_MULT_TIER_4
-	damage_mult = BASE_BULLET_DAMAGE_MULT + BULLET_DAMAGE_MULT_TIER_6
+	damage_mult = BASE_BULLET_DAMAGE_MULT + BULLET_DAMAGE_MULT_TIER_8
 	recoil_unwielded = RECOIL_AMOUNT_TIER_4
 	damage_falloff_mult = 0
 	scatter = SCATTER_AMOUNT_TIER_8