test/data: rename non-ascii/😻.txt

Prior to this, pkg.go.dev would reject the repo (due to an error from
golang.org/x/mod/module). See https://go.dev/play/p/cGG7piSw1Wl and
https://proxy.golang.org/github.com/google/wuffs/@v/v0.3.4.info also
said:

not found: create zip: test/data/non-ascii/😻.txt: malformed file path
"test/data/non-ascii/😻.txt": invalid char '😻'

"b/test/data/non-ascii/astral-\360\235\224\270.txt"

diff --git "a/test/data/non-ascii/astral-\360\235\224\270.txt" "b/test/data/non-ascii/astral-\360\235\224\270.txt"
new file mode 100644
index 0000000..8ad2a04
--- /dev/null
+++ "b/test/data/non-ascii/astral-\360\235\224\270.txt"
@@ -0,0 +1,7 @@
+𝔸 U+1D538 MATHEMATICAL DOUBLE-STRUCK CAPITAL A. UTF-8: [F0 9D 94 B8].
+
+This code point is outside of the Unicode BMP (Basic Multilingual Plane), but
+its Unicode Category is Lu (Letter, uppercase), so it is still a valid file
+path in terms of pkg.go.dev and its golang.org/x/mod/module package:
+
+https://github.com/golang/mod/blob/dc121ce20ffab6bb810a0f231cfa9c24d3e51b29/module/module.go#L293

"b/test/data/non-ascii/greek-\316\261\316\262.txt"

diff --git "a/test/data/non-ascii/\316\261\316\262.txt" "b/test/data/non-ascii/greek-\316\261\316\262.txt"
similarity index 100%
rename from "test/data/non-ascii/\316\261\316\262.txt"
rename to "test/data/non-ascii/greek-\316\261\316\262.txt"

"a/test/data/non-ascii/\360\237\230\273.txt"

diff --git "a/test/data/non-ascii/\360\237\230\273.txt" "b/test/data/non-ascii/\360\237\230\273.txt"
deleted file mode 100644
index 98aeba7..0000000
--- "a/test/data/non-ascii/\360\237\230\273.txt"
+++ /dev/null
@@ -1,3 +0,0 @@
-😻 U+1F63B SMILING CAT FACE WITH HEART-SHAPED EYES. UTF-8: [F0 9F 98 BB].
-
-This code point is outside of the Unicode BMP (Basic Multilingual Plane).