[FEATURE REQUEST] Add dependency review (automatically check PR's for security

### I have searched through the issues and didn't find my problem.

- [X] Confirm

### Problem

[Dependency review](https://docs.github.com/en/code-security/supply-chain-security/understanding-your-software-supply-chain/about-dependency-review) adds the ability to block pull requests that introduce vulnerable dependencies. We can select what order of severity we want to accept too, so that for example minor security vulnerabilities are ignored, while critical ones are handled.

There's not much need for running this for each icon request though, since they never introduce new dependencies. So we can just run it every time the PR is not an icon request.

### Possible Solution

This is the documentation that shows how you can [configure dependency review](https://docs.github.com/en/code-security/supply-chain-security/understanding-your-software-supply-chain/configuring-dependency-review).

The documentation provides a little snippet which I've modified it to fit what I think we want. More precisely I've changed the following:
- Added an if statement so it only runs on PR's that aren't icon requests:
- Changed `fail-on-severity` from `critical` to `high`

```yaml
name: 'Dependency Review'
on: [pull_request]

permissions:
contents: read

jobs:
dependency-review:
runs-on: ubuntu-latest
if: ${{!startsWith(github.event.pull_request.title, 'new icon') || startsWith(github.event.pull_request.title, 'update icon')}} # only run if not an icon PR
steps:
- name: 'Checkout Repository'
uses: actions/checkout@v3
- name: Dependency Review
uses: actions/dependency-review-action@v2
with:
# Possible values: "critical", "high", "moderate", "low"
fail-on-severity: high

# You can only can only include one of these two options: `allow-licenses` and `deny-licences`
# ([String]). Only allow these licenses (optional)
# Possible values: Any `spdx_id` value(s) from https://docs.github.com/en/rest/licenses
# allow-licenses: GPL-3.0, BSD-3-Clause, MIT

# ([String]). Block the pull request on these licenses (optional)
# Possible values: Any `spdx_id` value(s) from https://docs.github.com/en/rest/licenses
# deny-licenses: LGPL-2.0, BSD-2-Clause

```

### Additional information

We might also want to deny (or only accept) certain licenses. I'm no licensing expert however, so I'll leave that up to the community to decide what makes the most sense.

Please discuss in the comments below what you think about the request, and the licenses in particular.