Downgrade minimum version of glsl

pkg/gl_helpers/fragment_shader.go

@@ -1,7 +1,7 @@
 package gl_helpers
 
 var FragmentShaderSource = `
-#version 330
+#version 140
 
 in vec3 fragPos;
 in vec3 fragNormal;

pkg/gl_helpers/vertex_shader.go

@@ -1,7 +1,7 @@
 package gl_helpers
 
 var VertexShaderSource = `
-#version 330
+#version 140
 uniform mat4 projection;
 uniform mat4 camera;
 uniform mat4 model;