chore(deps): update dock.mau.dev/mautrix/discord docker tag to v0.7.6 (#4035)

This PR contains the following updates:

| Package | Update | Change |
|---|---|---|
| dock.mau.dev/mautrix/discord | patch | `v0.7.5` → `v0.7.6` |

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Reviewed-on: #4035
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clusters/cl01tl/helm/matrix-synapse/values.yaml

@@ -260,7 +260,7 @@ mautrix-discord:
         main:
           image:
             repository: dock.mau.dev/mautrix/discord
-            tag: v0.7.5
+            tag: v0.7.6
             pullPolicy: IfNotPresent
           resources:
             requests: