[DPE-5063] Update MySQL to v8.0.40 (#207)

## Issue
The new 8.0/edge snap updates MySQL to v8.0.40

## Solution
Update the snap and update MySQL to 8.0.40

Author: shayancanonical

src/snap.py

@@ -25,8 +25,8 @@
 _SNAP_NAME = "charmed-mysql"
 REVISIONS: typing.Dict[str, str] = {
     # Keep in sync with `workload_version` file
-    "x86_64": "121",
-    "aarch64": "122",
+    "x86_64": "128",
+    "aarch64": "127",
 }
 revision = REVISIONS[platform.machine()]
 _snap = snap_lib.SnapCache()[_SNAP_NAME]

workload_version

@@ -1 +1 @@
-8.0.39
+8.0.40