Update to electron 13

and to seshat 2.3.0 which supports it.

hak/matrix-seshat/build.js

@@ -258,6 +258,9 @@ async function buildSqlCipherUnix(hakEnv, moduleInfo) {
 }
 
 async function buildMatrixSeshat(hakEnv, moduleInfo) {
+    // seshat now uses n-api so we shouldn't need to specify a node version to
+    // build against, but it does seems to still need something in here, so leaving
+    // it for now: we should confirm how much of this it still actually needs.
     const env = hakEnv.makeGypEnv();
 
     if (!hakEnv.isLinux()) {

package.json

@@ -77,12 +77,12 @@
     "typescript": "^4.1.3"
   },
   "hakDependencies": {
-    "matrix-seshat": "^2.2.3",
+    "matrix-seshat": "^2.3.0",
     "keytar": "^5.6.0"
   },
   "build": {
     "appId": "im.riot.app",
-    "electronVersion": "12.0.14",
+    "electronVersion": "13.1.6",
     "files": [
       "package.json",
       {