Make CI run on changes to non-code files as well (#2130)

The repository is configured such that specific checks are required to pass before merging; since CI doesn't run on PRs that don't change code, they can't be merged without administrator intervention.

Also, while this definition is currently correct, we might in the future change something so that changes to other files (like markdown files) really should be run through CI.

And example of that could be:
```rust
#[cfg(doctest)]
#[doc = include_str!("../README.md")]
extern "C" {}
```

.github/workflows/ci.yml

@@ -2,16 +2,8 @@ name: CI
 
 on:
   pull_request:
-    paths:
-      - '**.rs'
-      - '**.toml'
-      - '.github/workflows/ci.yml'
   push:
     branches: [master]
-    paths:
-      - '**.rs'
-      - '**.toml'
-      - '.github/workflows/ci.yml'
 
 jobs:
   Check_Formatting: