feat: add nginx variant #446

Job	Run time
generate-matrix	4s
PHP FPM 8.1	33s
PHP FPM 8.2	36s
PHP FPM 8.3	35s
Build Nginx with 8.1	33s
PHP FPM 8.1 with OpenTelemetry	33s
Build Nginx with 8.2	29s
Build Caddy with 8.1	38s
PHP FPM 8.2 with OpenTelemetry	34s
Build Nginx with 8.3	25s
Build Caddy with 8.2	27s
PHP FPM 8.3 with OpenTelemetry	34s
Build Caddy with 8.3	38s
Test Image with Webserver caddy	1m 46s
Test Image with Webserver nginx	1m 45s
Build Caddy 8.1 with OpenTelemetry	38s
Build Nginx with 8.1 with OpenTelemetry	25s
Build Caddy 8.2 with OpenTelemetry	47s
Build Nginx with 8.2 with OpenTelemetry	25s
Build Caddy 8.3 with OpenTelemetry	41s
Build Nginx with 8.3 with OpenTelemetry	22s
	13m 28s

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