Bump version to 2.28.5

```
./scripts/bump_version.sh --version 2.28.5
```

Signed-off-by: Minos Galanakis <minos.galanakis@arm.com>
diff --git a/doxygen/input/doc_mainpage.h b/doxygen/input/doc_mainpage.h
index d19f93e..0cad01b 100644
--- a/doxygen/input/doc_mainpage.h
+++ b/doxygen/input/doc_mainpage.h
@@ -22,7 +22,7 @@
  */
 
 /**
- * @mainpage Mbed TLS v2.28.4 API Documentation
+ * @mainpage Mbed TLS v2.28.5 API Documentation
  *
  * This documentation describes the internal structure of Mbed TLS.  It was
  * automatically generated from specially formatted comment blocks in
diff --git a/doxygen/mbedtls.doxyfile b/doxygen/mbedtls.doxyfile
index adad131..f6f160d 100644
--- a/doxygen/mbedtls.doxyfile
+++ b/doxygen/mbedtls.doxyfile
@@ -1,4 +1,4 @@
-PROJECT_NAME           = "Mbed TLS v2.28.4"
+PROJECT_NAME           = "Mbed TLS v2.28.5"
 OUTPUT_DIRECTORY       = ../apidoc/
 FULL_PATH_NAMES        = NO
 OPTIMIZE_OUTPUT_FOR_C  = YES