bump up CMake minimum version required to 3.15

[apwojcik]

The PR from the series to enable MIGraphX on Windows.

[migraphx-bot]

Test	Batch	Rate new 39827d	Rate old 697709	Diff	Compare
torchvision-resnet50	64	895.23	895.75	-0.06%	✅
torchvision-resnet50_fp16	64	5,312.61	5,314.47	-0.03%	✅
torchvision-densenet121	32	1,125.96	1,126.59	-0.06%	✅
torchvision-densenet121_fp16	32	3,282.85	3,284.10	-0.04%	✅
torchvision-inceptionv3	32	592.94	592.96	-0.00%	✅
torchvision-inceptionv3_fp16	32	2,529.88	2,517.46	0.49%	✅
cadene-inceptionv4	16	329.44	329.93	-0.15%	✅
cadene-resnext64x4	16	396.91	393.50	0.87%	✅
slim-mobilenet	64	7,134.27	7,139.23	-0.07%	✅
slim-nasnetalarge	64	159.98	159.91	0.04%	✅
slim-resnet50v2	64	1,089.86	1,089.62	0.02%	✅
bert-mrpc-onnx	8	718.73	719.61	-0.12%	✅
bert-mrpc-tf	1	370.54	372.21	-0.45%	✅
pytorch-examples-wlang-gru	1	307.64	307.29	0.11%	✅
pytorch-examples-wlang-lstm	1	312.81	313.39	-0.19%	✅
torchvision-resnet50_1	1	91.73	91.58	0.17%	✅
torchvision-inceptionv3_1	1	128.88	129.13	-0.19%	✅
cadene-dpn92_1	1	335.52	335.84	-0.10%	✅
cadene-resnext101_1	1	236.59	236.90	-0.13%	✅
slim-vgg16_1	1	53.39	53.37	0.05%	✅
slim-mobilenet_1	1	1,511.43	1,526.43	-0.98%	✅
slim-inceptionv4_1	1	101.99	99.82	2.17%	✅
onnx-taau-downsample	1	316.67	316.86	-0.06%	✅
dlrm-criteoterabyte	1	21.44	21.44	0.02%	✅
dlrm-criteoterabyte_fp16	1	39.99	39.97	0.05%	✅
agentmodel	1	5,865.21	5,625.18	4.27%	🔆
unet_fp16	2	52.77	52.81	-0.08%	✅

Check results before merge 🔆

[migraphx-bot]

    :white_check_mark:bert-mrpc-onnx: PASSED: MIGraphX meets tolerance

    :white_check_mark:bert-mrpc-tf: PASSED: MIGraphX meets tolerance

    :white_check_mark:pytorch-examples-wlang-gru: PASSED: MIGraphX meets tolerance

    :white_check_mark:pytorch-examples-wlang-lstm: PASSED: MIGraphX meets tolerance

    :white_check_mark:torchvision-resnet50_1: PASSED: MIGraphX meets tolerance

    :white_check_mark:torchvision-inceptionv3_1: PASSED: MIGraphX meets tolerance

🔴cadene-dpn92_1: FAILED: MIGraphX is not within tolerance - check verbose output

    :white_check_mark:cadene-resnext101_1: PASSED: MIGraphX meets tolerance

    :white_check_mark:slim-vgg16_1: PASSED: MIGraphX meets tolerance

    :white_check_mark:slim-mobilenet_1: PASSED: MIGraphX meets tolerance

    :white_check_mark:slim-inceptionv4_1: PASSED: MIGraphX meets tolerance

    :white_check_mark:dlrm-criteoterabyte: PASSED: MIGraphX meets tolerance

    :white_check_mark:agentmodel: PASSED: MIGraphX meets tolerance

    :white_check_mark:unet: PASSED: MIGraphX meets tolerance

[codecov]

Codecov Report

Merging #1888 (c1ecb49) into develop (c04fbc9) will not change coverage.
The diff coverage is n/a.

❗ Current head c1ecb49 differs from pull request most recent head ce4310f. Consider uploading reports for the commit ce4310f to get more accurate results

@@           Coverage Diff            @@
##           develop    #1888   +/-   ##
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  Coverage    91.36%   91.36%           
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  Files          420      420           
  Lines        15554    15554           
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  Hits         14211    14211           
  Misses        1343     1343