build-aux: Update Flatpak module for mbedTLS to v3.6.4

MbedTLS v3.6.2 has an issue with fragmented TLS 1.3 handshakes, causing
some RTMPS streams to fail to connect. Update to mbedTLS v3.6.4 where
this is fixed.

build-aux/modules/10-mbedtls.json

@@ -16,9 +16,9 @@
     "sources": [
         {
             "type": "git",
-            "url": "https://github.com/ARMmbed/mbedtls.git",
-            "commit": "107ea89daaefb9867ea9121002fbbdf926780e98",
-            "tag": "v3.6.2"
+            "url": "https://github.com/Mbed-TLS/mbedtls.git",
+            "commit": "c765c831e5c2a0971410692f92f7a81d6ec65ec2",
+            "tag": "v3.6.4"
         }
     ]
 }