Add go-sqlite3 dependency to go.mod
Fixes this "go mod tidy" error on master:
```
git.monogon.dev/source/nexantic.git imports
github.com/rubenv/sql-migrate/sql-migrate imports
github.com/mattn/go-sqlite3: module github.com/mattn/go-sqlite3@latest found (v2.0.0+incompatible), but does not contain package github.com/mattn/go-sqlite3
```
The fix was to run `go mod tidy` using Go 1.12, since Go 1.13 got confused
about the sqlite3 package (there is no v2.0.0 - I suspect an issue with
the proxy). Notably, neither sql-migrate nor go-sqlite3 use Go modules,
and there's no way to get rid of the dependency:
https://github.com/rubenv/sql-migrate/blob/aff46b65bb7f71e015dc28dc2edd083737985dfb/sql-migrate/config.go#L17
Adds a `go mod tidy` invocation to gazelle.sh.
Test Plan: Ran gazelle.sh.
X-Origin-Diff: phab/D268
GitOrigin-RevId: 843710797dc2bccc2c7efdc249ac2b28a23c3fae
diff --git a/scripts/gazelle.sh b/scripts/gazelle.sh
index 12c60bc..d6e7cee 100755
--- a/scripts/gazelle.sh
+++ b/scripts/gazelle.sh
@@ -1,5 +1,7 @@
#!/bin/bash
# gazelle.sh regenerates BUILD.bazel files for Go source files.
+set -euo pipefail
+bazel run //:go mod tidy
bazel run //:gazelle -- update
bazel run //:gazelle -- update-repos -from_file=go.mod -to_macro=repositories.bzl%go_repositories -prune=true