[bug] Cannot resolve conflicts in conanfile.txt

### Describe the bug

I just created the `conanfile.txt` at the bottom for a project.
When installing it. conan informs me there is a version conflict between stb/cci.20230920 and stb/cci.20240531.
Looking through the documentation, I don't see a way to resolve this in the txt file.

I believe overriding packages should be do-able from the txt files, and does not require a conversion to py files.

Also, the error messages contains: `Run conan graph info with your recipe and add --format=html to inspect the graph errors in an easier to visualize way.`
But when I add `--format=html`, no html files are generated.

### How to reproduce it

**conanfile.txt**
```
[requires]
miniz/3.0.2
nlohmann_json/3.11.3
stb/cci.20240531
libsquish/1.15
glew/2.2.0
assimp/5.4.2
fmt/11.0.2

[generators]
CMakeDeps
CMakeToolchain
```

```
$ conan install . --output-folder=build --build=missing
```