Raise abs_tolerance number for CL/DirectConvolution3D fp16 tests

Resolves: COMPMID-6255
Signed-off-by: Ramy Elgammal <ramy.elgammal@arm.com>
Change-Id: I602bcbf58f78e7384789cd077cfc3b549d53463e
Reviewed-on: https://review.mlplatform.org/c/ml/ComputeLibrary/+/9637
Benchmark: Arm Jenkins <bsgcomp@arm.com>
Reviewed-by: SiCong Li <sicong.li@arm.com>
Comments-Addressed: Arm Jenkins <bsgcomp@arm.com>
Tested-by: Arm Jenkins <bsgcomp@arm.com>
diff --git a/tests/validation/CL/Convolution3D.cpp b/tests/validation/CL/Convolution3D.cpp
index ae9c479..a284856 100644
--- a/tests/validation/CL/Convolution3D.cpp
+++ b/tests/validation/CL/Convolution3D.cpp
@@ -39,7 +39,7 @@
 namespace
 {
 const RelativeTolerance<half>        rel_tolerance_fp16(half(0.2)); /**< Relative tolerance for FP16 tests */
-constexpr float                      abs_tolerance_fp16(0.02f);     /**< Absolute tolerance for FP16 tests */
+constexpr float                      abs_tolerance_fp16(0.05f);     /**< Absolute tolerance for FP16 tests */
 constexpr RelativeTolerance<float>   rel_tolerance_fp32(0.05f);     /**< Relative tolerance for FP32 tests */
 constexpr float                      abs_tolerance_fp32(0.0001f);   /**< Absolute tolerance for FP32 tests*/
 constexpr AbsoluteTolerance<uint8_t> abs_tolerance_qasymm8(1);      /**< Absolute tolerance for quantized tests */