Add Int8 support (since gdal>=3.7.0)

doc_test.go

@@ -289,6 +289,14 @@ func Example_rasterTutorial() {
 	poDstDS.Bands()[0].Write(0, 0, abyRaster, 512, 512)
 	poDstDS.Close()
 
+	if godal.Int8 != -1 { // Test valid for gdal > 3.7.0
+		poDstDSInt8, _ := godal.Create(godal.GTiff, pszDstFilename, 1, godal.Int8, 512, 512)
+		defer poDstDSInt8.Close() //Close can be defered / called more than once (second+ calls are no-ops)
+
+		// ... now populate with data
+		poDstDSInt8.Bands()[0].Write(0, 0, abyRaster, 512, 512)
+		poDstDSInt8.Close()
+	}
 	// Output:
 	// Size is 10x10x3
 	// Projection is 'GEOGCS["WGS 84",DATU...'

godal.go

@@ -45,6 +45,8 @@ const (
 	Byte = DataType(C.GDT_Byte)
 	//UInt16 DataType
 	UInt16 = DataType(C.GDT_UInt16)
+	//Int8 DataType
+	Int8 = DataType(C.GDT_Int8)
 	//Int16 DataType
 	Int16 = DataType(C.GDT_Int16)
 	//UInt32 DataType

godal.h

@@ -25,6 +25,10 @@
 
 #if GDAL_VERSION_NUM < 3000000
 	#error "this code is only compatible with gdal version >= 3.0"
+#elif GDAL_VERSION_NUM < GDAL_COMPUTE_VERSION(3, 7, 0)
+typedef enum {
+    /*! 8-bit signed integer (GDAL >= 3.7) */ GDT_Int8 = -1
+} FutureGDALDataType;
 #endif
 
 #ifdef __cplusplus