Change seen_by in msgdata_template to not be null

The sender has always seen their message, haven't they?

Cargo.lock

@@ -814,9 +814,9 @@ checksum = "e2abad23fbc42b3700f2f279844dc832adb2b2eb069b2df918f455c4e18cc646"
 
 [[package]]
 name = "libc"
-version = "0.2.109"
+version = "0.2.111"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f98a04dce437184842841303488f70d0188c5f51437d2a834dc097eafa909a01"
+checksum = "8e167738f1866a7ec625567bae89ca0d44477232a4f7c52b1c7f2adc2c98804f"
 
 [[package]]
 name = "libsqlite3-sys"
@@ -1054,9 +1054,9 @@ checksum = "28988d872ab76095a6e6ac88d99b54fd267702734fd7ffe610ca27f533ddb95a"
 
 [[package]]
 name = "openssl-sys"
-version = "0.9.71"
+version = "0.9.72"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "7df13d165e607909b363a4757a6f133f8a818a74e9d3a98d09c6128e15fa4c73"
+checksum = "7e46109c383602735fa0a2e48dd2b7c892b048e1bf69e5c3b1d804b7d9c203cb"
 dependencies = [
  "autocfg",
  "cc",
@@ -1317,9 +1317,9 @@ dependencies = [
 
 [[package]]
 name = "ryu"
-version = "1.0.7"
+version = "1.0.9"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "254df5081ce98661a883445175e52efe99d1cb2a5552891d965d2f5d0cad1c16"
+checksum = "73b4b750c782965c211b42f022f59af1fbceabdd026623714f104152f1ec149f"
 
 [[package]]
 name = "safemem"

src/sqlite/msgdata_template.sql

@@ -7,6 +7,6 @@ CREATE TABLE msgdata_{chat_id} (
 	msg_type INTEGER NOT NULL,
 	content TEXT,
 	hide_for TEXT,
-	seen_by TEXT,
+	seen_by TEXT NOT NULL,
 	CONSTRAINT PK_msgdata_{chat_id} PRIMARY KEY (msg_id, timestamp)
 );