Use smaller uint dwp functions where possible

Sources/GZip/GzipArchive.swift

@@ -82,7 +82,7 @@ public class GzipArchive: Archive {
         bitReader.align()
 
         let crc32 = bitReader.uint32()
-        let isize = bitReader.uint64(count: 4)
+        let isize = bitReader.uint32()
         guard UInt64(memberData.count) % (UInt64(1) << 32) == isize else { throw GzipError.wrongISize }
 
         return Member(header: header, data: memberData,

Sources/GZip/GzipHeader.swift

@@ -136,7 +136,7 @@ public struct GzipHeader {
         // Some archives may contain 2-bytes checksum
         if flags.contains(.fhcrc) {
             // Note: it is not actual CRC-16, it is just two least significant bytes of CRC-32.
-            let crc16 = pointerData.uint32(count: 2)
+            let crc16 = pointerData.uint16()
             guard CheckSums.crc32(headerBytes) & 0xFFFF == crc16 else { throw GzipError.wrongHeaderCRC }
         }
     }