[Build] v1.20.0 min GCC version can't build on armv8

### Describe the issue

The GCC version is checked to be at least version 9 in the `CMakeLists.txt`. https://github.com/microsoft/onnxruntime/blob/c4fb724e810bb496165b9015c77f402727392933/cmake/CMakeLists.txt#L69

When building on armv8 with GCC 9 the check further down fails https://github.com/microsoft/onnxruntime/blob/c4fb724e810bb496165b9015c77f402727392933/cmake/CMakeLists.txt#L693

It seems the feature modifier `bf16` was introduced in GCC 10 [see here](https://gcc.gnu.org/onlinedocs/gcc-10.5.0/gcc/AArch64-Options.html#aarch64-feature-modifiers).  
If I'm not mistaken the minimum GCC version checked for should be rather be 10 instead of 9.

### Urgency

_No response_

### Target platform

armv8

### Build script

Using [`build.py`](https://github.com/microsoft/onnxruntime/blob/c4fb724e810bb496165b9015c77f402727392933/tools/ci_build/build.py) with ` --parallel 4 --config Release --build_dir build --cmake_extra_defines FETCHCONTENT_TRY_FIND_PACKAGE_MODE=NEVER`

### Error / output

```
-- Performing Test HAS_ARM64_BFLOAT16 - Failed
CMake Error at CMakeLists.txt:695 (message):
  The compiler doesn't support BFLOAT16!!!
```

### Visual Studio Version

_No response_

### GCC / Compiler Version

9.5.0

[]