[Bug]: FloatingEqMatcher doesn't work with const float value types

### Describe the issue

`FloatingEqMatcher` doesn't work with `const` float value types. See https://godbolt.org/z/zexhra9eG. A const conversion is missing

### Steps to reproduce the problem

https://godbolt.org/z/zexhra9eG

### What version of GoogleTest are you using?

trunk

### What operating system and version are you using?

(see godbolt repro)

### What compiler and version are you using?

clang 15

### What build system are you using?

(see godbolt repro)

### Additional context

_No response_

Start with FloatingEqMatcher and reproduce the failure using the linked Godbolt example with clang 15 and the trunk version of GoogleTest. Trace the const float value-type conversion involved and verify that the Godbolt reproduction succeeds after the issue is addressed.

Written by the indexing model from the issue text.