`HttpVersion`, `RtspVersions` and `RtspMethods` all uppercase their
input via `String.toUpperCase()` without an explicit `Locale`. The JVM
default locale governs that call, and in Turkish (`tr_TR`) the ASCII
letter `'i'` uppercases to `'İ'` (U+0130), not `'I'`.

Concretely, on a Turkish-locale JVM:

- `RtspMethods.valueOf("describe")` produces `"DESCRİBE"` after the
uppercase, fails the cache lookup, falls through to
`HttpMethod.valueOf(...)`, and throws `IllegalArgumentException: Illegal
character in HTTP Method: 0x130` for what is otherwise a perfectly valid
RTSP method. Same for `"redirect"` (`REDİRECT`).
- `HttpVersion.valueOf("icap/1.0")` and the `(protocolName, major,
minor, ...)` constructor with `"icap"` end up with `protocolName()`
containing U+0130 instead of plain ASCII `'I'`. The version no longer
matches its own canonical form.

The protocol grammars are ASCII-only (RFC 7230 §2.6 / RFC 2326 §1.4), so
the uppercase has no business consulting the JVM locale.

Pin every `String.toUpperCase()` in these three classes to `Locale.US`:

-
`codec-http/src/main/java/io/netty/handler/codec/http/HttpVersion.java`
- `(text, strict, keepAliveDefault)` constructor — line that normalizes
the supplied protocol string.
- `(protocolName, major, minor, keepAliveDefault, bytes)` constructor —
line that normalizes the supplied protocol name.
-
`codec-http/src/main/java/io/netty/handler/codec/rtsp/RtspMethods.java`
- `valueOf(String name)` — line that normalizes the supplied RTSP method
name before the cache lookup.
-
`codec-http/src/main/java/io/netty/handler/codec/rtsp/RtspVersions.java`
- `valueOf(String text)` — line that normalizes the supplied version
string before comparing to the cached `RTSP/1.0`.

`AsciiString.toUpperCase()` / `AsciiString.toLowerCase()` paths in the
same module are already ASCII-byte-level and not affected by this issue,
so they are left alone.

`codec-http/src/test/java/io/netty/handler/codec/http/HttpVersionParsingTest.java`:

| Change Point | Test |
|--------------|------|
| `HttpVersion.valueOf(text)` under Turkish locale |
`testLowercaseIotaProtocolNameUnderTurkishLocale` — installs
`Locale.setDefault(new Locale("tr","TR"))` (restored in `finally`) and
asserts `valueOf("icap/1.0")` returns a version whose `protocolName()`
is the ASCII `"ICAP"` and whose `text()` is `"ICAP/1.0"`. |
| `HttpVersion(protocolName, major, minor, ...)` under Turkish locale |
`testProtocolNameConstructorUnderTurkishLocale` — same locale setup,
asserts `new HttpVersion("icap", 1, 0, true)` ends up with
`protocolName()` = `"ICAP"` and `text()` = `"ICAP/1.0"`. |

New
`codec-http/src/test/java/io/netty/handler/codec/rtsp/RtspMethodsTest.java`:

| Change Point | Test |
|--------------|------|
| Cached uppercase lookup still works |
`valueOfReturnsCachedInstanceForUppercaseName` |
| Lowercase normalization under default locale |
`valueOfNormalizesLowercaseInputUnderUsLocale` |
| Lowercase normalization under Turkish locale |
`valueOfNormalizesLowercaseInputUnderTurkishLocale` — installs `tr_TR`,
calls `valueOf("describe")` and `valueOf("redirect")`, asserts both
resolve to the cached `DESCRIBE` / `REDIRECT` instances. |

All three Turkish-locale tests fail deterministically against the
unfixed code (one with a clean assertion failure, the `RtspMethods` one
with `IllegalArgumentException: Illegal character in HTTP Method:
0x130`) and pass after the `Locale.US` change.

Verification:

```
mvn -pl codec-http -am test -Dtest='HttpVersionParsingTest,RtspMethodsTest' -Dsurefire.failIfNoSpecifiedTests=false
```

- Behavior on en/CJK/most locales: unchanged (the previous
default-locale uppercase already produced ASCII).
- Behavior on Turkish (and other locales with non-ASCII case mappings,
e.g. Azerbaijani): RTSP method parsing and HTTP-derived version parsing
of lowercase or mixed-case inputs now succeed instead of throwing or
returning a U+0130-tainted result.
- API: no signature change. All callers continue to use
`valueOf(String)` / the existing constructors.
- Risk: bounded — `Locale.US` is the standard Netty pattern for
protocol-string normalization (see e.g.
`WebSocketClientHandshaker.java:761`).