Fix PEM callback compatibility and bump version to 0.4.0

src/main/jwt_full/private/crypto/pem.nim

@@ -3,7 +3,7 @@ import bearssl
 # Taken from  nim-bearssl/decls.nim
 {.pragma: bearSslFunc, cdecl, gcsafe, noSideEffect, raises: [].}
 
-type BearPemDecoderCallback* = proc(destCtx: pointer, src: pointer, dataLen: uint) {.bearSslFunc.}
+type BearPemDecoderCallback* = proc(destCtx: pointer, src: pointer, dataLen: csize_t) {.bearSslFunc.}
 
 proc decodePem*(
     pem: string,