Upgrade to Alpine Linux v3.19 (#3541)

- **PR Description**

Alpine v3.15 is out-of-date since 2023-11-01 and is not getting any
security updates anymore: https://alpinelinux.org/releases/

- **Please check if the PR fulfills these requirements**

* [x] Cheatsheets are up-to-date (run `go generate ./...`)
* [x] Code has been formatted (see
[here](https://github.com/jesseduffield/lazygit/blob/master/CONTRIBUTING.md#code-formatting))
* [x] Tests have been added/updated (see
[here](https://github.com/jesseduffield/lazygit/blob/master/pkg/integration/README.md)
for the integration test guide)
* [x] Text is internationalised (see
[here](https://github.com/jesseduffield/lazygit/blob/master/CONTRIBUTING.md#internationalisation))
* [x] Docs (specifically `docs/Config.md`) have been updated if
necessary
* [x] You've read through your own file changes for silly mistakes etc

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Dockerfile

@@ -9,7 +9,7 @@ RUN go mod download
 COPY . .
 RUN CGO_ENABLED=0 GOOS=linux go build
 
-FROM alpine:3.15
+FROM alpine:3.19
 RUN apk add --no-cache -U git xdg-utils
 WORKDIR /go/src/github.com/jesseduffield/lazygit/
 COPY --from=build /go/src/github.com/jesseduffield/lazygit ./